1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2016 Free Software
4 @c See file emacs.texi for copying conditions.
6 @chapter Miscellaneous Commands
8 This chapter contains several brief topics that do not fit anywhere
9 else: reading Usenet news, host and network security,
10 viewing PDFs and other such documents, web
11 browsing, running shell commands and shell subprocesses, using a
12 single shared Emacs for utilities that expect to run an editor as a
13 subprocess, printing, sorting text, editing binary files, saving an
14 Emacs session for later resumption, recursive editing level, following
15 hyperlinks, and various diversions and amusements.
29 Gnus is an Emacs package primarily designed for reading and posting
30 Usenet news. It can also be used to read and respond to messages from
31 a number of other sources---email, remote directories, digests, and so
32 on. Here we introduce Gnus and describe several basic features.
34 For full details, see @ref{Top, Gnus,, gnus, The Gnus Manual}.
37 For full details on Gnus, type @kbd{C-h i} and then select the Gnus
42 * Buffers of Gnus:: The group, summary, and article buffers.
43 * Gnus Startup:: What you should know about starting Gnus.
44 * Gnus Group Buffer:: A short description of Gnus group commands.
45 * Gnus Summary Buffer:: A short description of Gnus summary commands.
49 @subsection Gnus Buffers
51 Gnus uses several buffers to display information and to receive
52 commands. The three most commonly-used Gnus buffers are the
53 @dfn{group buffer}, the @dfn{summary buffer} and the @dfn{article
56 The @dfn{group buffer} contains a list of article sources (e.g.,
57 newsgroups and email inboxes), which are collectively referred to as
58 @dfn{groups}. This is the first buffer Gnus displays when it starts
59 up. It normally displays only the groups to which you subscribe and
60 that contain unread articles. From this buffer, you can select a
63 The @dfn{summary buffer} lists the articles in a single group,
64 showing one article per line. By default, it displays each article's
65 author, subject, and line
70 number, but this is customizable; @xref{Summary Buffer Format,,, gnus,
73 The summary buffer is created when you select a group in the group
74 buffer, and is killed when you exit the group.
76 From the summary buffer, you can choose an article to view. The
77 article is displayed in the @dfn{article buffer}. In normal Gnus
78 usage, you view this buffer but do not select it---all useful Gnus
79 commands can be invoked from the summary buffer. But you can select
80 the article buffer, and execute Gnus commands from it, if you wish.
83 @subsection When Gnus Starts Up
86 @cindex @file{.newsrc} file
87 If your system has been set up for reading Usenet news, getting
88 started with Gnus is easy---just type @kbd{M-x gnus}.
90 On starting up, Gnus reads your @dfn{news initialization file}: a
91 file named @file{.newsrc} in your home directory which lists your
92 Usenet newsgroups and subscriptions (this file is not unique to Gnus;
93 it is used by many other newsreader programs). It then tries to
94 contact the system's default news server, which is typically specified
95 by the @env{NNTPSERVER} environment variable.
97 If your system does not have a default news server, or if you wish
98 to use Gnus for reading email, then before invoking @kbd{M-x gnus} you
99 need to tell Gnus where to get news and/or mail. To do this,
100 customize the variables @code{gnus-select-method} and/or
101 @code{gnus-secondary-select-methods}.
103 See the Gnus manual for details.
106 @xref{Finding the News,,, gnus, The Gnus Manual}.
109 Once Gnus has started up, it displays the group buffer. By default,
110 the group buffer shows only a small number of @dfn{subscribed groups}.
111 Groups with other statuses---@dfn{unsubscribed}, @dfn{killed}, or
112 @dfn{zombie}---are hidden. The first time you start Gnus, any group
113 to which you are not subscribed is made into a killed group; any group
114 that subsequently appears on the news server becomes a zombie group.
116 To proceed, you must select a group in the group buffer to open the
117 summary buffer for that group; then, select an article in the summary
118 buffer to view its article buffer in a separate window. The following
119 sections explain how to use the group and summary buffers to do this.
121 To quit Gnus, type @kbd{q} in the group buffer. This automatically
122 records your group statuses in the files @file{.newsrc} and
123 @file{.newsrc.eld}, so that they take effect in subsequent Gnus
126 @node Gnus Group Buffer
127 @subsection Using the Gnus Group Buffer
129 The following commands are available in the Gnus group buffer:
132 @kindex SPC @r{(Gnus Group mode)}
133 @findex gnus-group-read-group
135 Switch to the summary buffer for the group on the current line.
137 @kindex l @r{(Gnus Group mode)}
138 @kindex A s @r{(Gnus Group mode)}
139 @findex gnus-group-list-groups
142 In the group buffer, list only the groups to which you subscribe and
143 which contain unread articles (this is the default listing).
145 @kindex L @r{(Gnus Group mode)}
146 @kindex A u @r{(Gnus Group mode)}
147 @findex gnus-group-list-all-groups
150 List all subscribed and unsubscribed groups, but not killed or zombie
153 @kindex A k @r{(Gnus Group mode)}
154 @findex gnus-group-list-all-groups
158 @kindex A z @r{(Gnus Group mode)}
159 @findex gnus-group-list-all-groups
163 @kindex u @r{(Gnus Group mode)}
164 @findex gnus-group-unsubscribe-current-group
165 @cindex subscribe groups
166 @cindex unsubscribe groups
168 Toggle the subscription status of the group on the current line
169 (i.e., turn a subscribed group into an unsubscribed group, or vice
170 versa). Invoking this on a killed or zombie group turns it into an
173 @kindex C-k @r{(Gnus Group mode)}
174 @findex gnus-group-kill-group
176 Kill the group on the current line. Killed groups are not recorded in
177 the @file{.newsrc} file, and they are not shown in the @kbd{l} or
180 @kindex DEL @r{(Gnus Group mode)}
182 Move point to the previous group containing unread articles.
184 @kindex n @r{(Gnus Group mode)}
185 @findex gnus-group-next-unread-group
186 @findex gnus-summary-next-unread-article
188 Move point to the next unread group.
190 @kindex p @r{(Gnus Group mode)}
191 @findex gnus-group-prev-unread-group
192 @findex gnus-summary-prev-unread-article
194 Move point to the previous unread group.
196 @kindex q @r{(Gnus Group mode)}
197 @findex gnus-group-exit
199 Update your Gnus settings, and quit Gnus.
202 @node Gnus Summary Buffer
203 @subsection Using the Gnus Summary Buffer
205 The following commands are available in the Gnus summary buffer:
208 @kindex SPC @r{(Gnus Summary mode)}
209 @findex gnus-group-read-group
211 If there is no article selected, select the article on the current
212 line and display its article buffer. Otherwise, try scrolling the
213 selected article buffer in its window; on reaching the end of the
214 buffer, select the next unread article.
216 Thus, you can read through all articles by repeatedly typing
219 @kindex DEL @r{(Gnus Summary mode)}
220 @findex gnus-summary-prev-page
222 Scroll the text of the article backwards.
224 @kindex n @r{(Gnus Summary mode)}
225 @findex gnus-group-next-unread-group
226 @findex gnus-summary-next-unread-article
228 Select the next unread article.
230 @kindex p @r{(Gnus Summary mode)}
231 @findex gnus-group-prev-unread-group
232 @findex gnus-summary-prev-unread-article
234 Select the previous unread article.
236 @kindex s @r{(Gnus Summary mode)}
237 @findex gnus-summary-isearch-article
239 Do an incremental search on the selected article buffer, as if you
240 switched to the buffer and typed @kbd{C-s} (@pxref{Incremental
243 @kindex M-s @r{(Gnus Summary mode)}
244 @findex gnus-summary-search-article-forward
245 @item M-s @var{regexp} @key{RET}
246 Search forward for articles containing a match for @var{regexp}.
248 @kindex q @r{(Gnus Summary mode)}
250 Exit the summary buffer and return to the group buffer.
254 @section Host Security
257 Emacs runs inside an operating system such as GNU/Linux, and relies on
258 the operating system to check security constraints such as accesses to
259 files. The default settings for Emacs are designed for typical use;
260 they may require some tailoring in environments where security is more
261 of a concern, or less of a concern, than usual. For example,
262 file-local variables can be risky, and you can set the variable
263 @code{enable-local-variables} to @code{:safe} or (even more
264 conservatively) to @code{nil}; conversely, if your files can all be
265 trusted and the default checking for these variables is irritating,
266 you can set @code{enable-local-variables} to @code{:all}. @xref{Safe
269 @xref{Security Considerations,,, elisp, The Emacs Lisp Reference
270 Manual}, for more information about security considerations when using
271 Emacs as part of a larger application.
273 @node Network Security
274 @section Network Security
275 @cindex network security manager
282 Whenever Emacs establishes any network connection, it passes the
283 established connection to the @dfn{Network Security Manager}
284 (@acronym{NSM}). @acronym{NSM} is responsible for enforcing the
285 network security under your control.
287 @vindex network-security-level
288 The @code{network-security-level} variable determines the security
289 level that @acronym{NSM} enforces. If its value is @code{low}, no
290 security checks are performed.
292 If this variable is @code{medium} (which is the default), a number of
293 checks will be performed. If as result @acronym{NSM} determines that
294 the network connection might not be trustworthy, it will make you
295 aware of that, and will ask you what to do about the network
298 You can decide to register a permanent security exception for an
299 unverified connection, a temporary exception, or refuse the connection
302 Below is a list of the checks done on the @code{medium} level.
306 @item unable to verify a @acronym{TLS} certificate
307 If the connection is a @acronym{TLS}, @acronym{SSL} or
308 @acronym{STARTTLS} connection, @acronym{NSM} will check whether
309 the certificate used to establish the identity of the server we're
310 connecting to can be verified.
312 While an invalid certificate is often the cause for concern (there
313 could be a Man-in-the-Middle hijacking your network connection and
314 stealing your password), there may be valid reasons for going ahead
315 with the connection anyway. For instance, the server may be using a
316 self-signed certificate, or the certificate may have expired. It's up
317 to you to determine whether it's acceptable to continue with the
320 @item a self-signed certificate has changed
321 If you've previously accepted a self-signed certificate, but it has
322 now changed, that could mean that the server has just changed the
323 certificate, but it might also mean that the network connection has
326 @item previously encrypted connection now unencrypted
327 If the connection is unencrypted, but it was encrypted in previous
328 sessions, this might mean that there is a proxy between you and the
329 server that strips away @acronym{STARTTLS} announcements, leaving the
330 connection unencrypted. This is usually very suspicious.
332 @item talking to an unencrypted service when sending a password
333 When connecting to an @acronym{IMAP} or @acronym{POP3} server, these
334 should usually be encrypted, because it's common to send passwords
335 over these connections. Similarly, if you're sending email via
336 @acronym{SMTP} that requires a password, you usually want that
337 connection to be encrypted. If the connection isn't encrypted,
338 @acronym{NSM} will warn you.
342 If @code{network-security-level} is @code{high}, the following checks
343 will be made, in addition to the above:
346 @item a validated certificate changes the public key
347 Servers change their keys occasionally, and that is normally nothing
348 to be concerned about. However, if you are worried that your network
349 connections are being hijacked by agencies who have access to pliable
350 Certificate Authorities which issue new certificates for third-party
351 services, you may want to keep track of these changes.
353 @item Diffie-Hellman low prime bits
354 When doing the public key exchange, the number of prime bits
355 should be high to ensure that the channel can't be eavesdropped on by
356 third parties. If this number is too low, you will be warned.
358 @item @acronym{RC4} stream cipher
359 The @acronym{RC4} stream cipher is believed to be of low quality and
360 may allow eavesdropping by third parties.
362 @item @acronym{SSL1}, @acronym{SSL2} and @acronym{SSL3}
363 The protocols older than @acronym{TLS1.0} are believed to be
364 vulnerable to a variety of attacks, and you may want to avoid using
365 these if what you're doing requires higher security.
368 Finally, if @code{network-security-level} is @code{paranoid}, you will
369 also be notified the first time @acronym{NSM} sees any new
370 certificate. This will allow you to inspect all the certificates from
371 all the connections that Emacs makes.
373 The following additional variables can be used to control details of
374 @acronym{NSM} operation:
377 @item nsm-settings-file
378 @vindex nsm-settings-file
379 This is the file where @acronym{NSM} stores details about connections.
380 It defaults to @file{~/.emacs.d/network-security.data}.
382 @item nsm-save-host-names
383 @vindex nsm-save-host-names
384 By default, host names will not be saved for non-@code{STARTTLS}
385 connections. Instead a host/port hash is used to identify connections.
386 This means that one can't casually read the settings file to see what
387 servers the user has connected to. If this variable is @code{t},
388 @acronym{NSM} will also save host names in the nsm-settings-file.
393 @section Document Viewing
397 @cindex PostScript file
398 @cindex OpenDocument file
399 @cindex Microsoft Office file
401 @cindex mode, DocView
402 @cindex document viewer (DocView)
403 @findex doc-view-mode
405 DocView mode is a major mode for viewing DVI, PostScript (PS), PDF,
406 OpenDocument, and Microsoft Office documents. It provides features
407 such as slicing, zooming, and searching inside documents. It works by
408 converting the document to a set of images using the @command{gs}
409 (GhostScript) or @command{mudraw}/@command{pdfdraw} (MuPDF) commands
410 and other external tools @footnote{For PostScript files, GhostScript
411 is a hard requirement. For DVI files, @code{dvipdf} or @code{dvipdfm}
412 is needed. For OpenDocument and Microsoft Office documents, the
413 @code{unoconv} tool is needed.}, and displaying those images.
415 @findex doc-view-toggle-display
416 @findex doc-view-toggle-display
417 @cindex doc-view-minor-mode
418 When you visit a document file that can be displayed with DocView
419 mode, Emacs automatically uses DocView mode @footnote{The needed
420 external tools for the document type must be available, and Emacs must
421 be running in a graphical frame and have PNG image support. If any of
422 these requirements is not fulfilled, Emacs falls back to another major
423 mode.}. As an exception, when you visit a PostScript file, Emacs
424 switches to PS mode, a major mode for editing PostScript files as
425 text; however, it also enables DocView minor mode, so you can type
426 @kbd{C-c C-c} to view the document with DocView. In either DocView
427 mode or DocView minor mode, repeating @kbd{C-c C-c}
428 (@code{doc-view-toggle-display}) toggles between DocView and the
429 underlying file contents.
431 @findex doc-view-open-text
432 When you visit a file which would normally be handled by DocView
433 mode but some requirement is not met (e.g., you operate in a terminal
434 frame or emacs has no PNG support), you are queried if you want to
435 view the document's contents as plain text. If you confirm, the
436 buffer is put in text mode and DocView minor mode is activated. Thus,
437 by typing @kbd{C-c C-c} you switch to the fallback mode. With another
438 @kbd{C-c C-c} you return to DocView mode. The plain text contents can
439 also be displayed from within DocView mode by typing @kbd{C-c C-t}
440 (@code{doc-view-open-text}).
442 You can explicitly enable DocView mode with the command @code{M-x
443 doc-view-mode}. You can toggle DocView minor mode with @code{M-x
444 doc-view-minor-mode}.
446 When DocView mode starts, it displays a welcome screen and begins
447 formatting the file, page by page. It displays the first page once
448 that has been formatted.
450 To kill the DocView buffer, type @kbd{k}
451 (@code{doc-view-kill-proc-and-buffer}). To bury it, type @kbd{q}
452 (@code{quit-window}).
455 * Navigation: DocView Navigation. Navigating DocView buffers.
456 * Searching: DocView Searching. Searching inside documents.
457 * Slicing: DocView Slicing. Specifying which part of a page is displayed.
458 * Conversion: DocView Conversion. Influencing and triggering conversion.
461 @node DocView Navigation
462 @subsection DocView Navigation
464 In DocView mode, you can scroll the current page using the usual
465 Emacs movement keys: @kbd{C-p}, @kbd{C-n}, @kbd{C-b}, @kbd{C-f}, and
468 @vindex doc-view-continuous
469 By default, the line-motion keys @kbd{C-p} and @kbd{C-n} stop
470 scrolling at the beginning and end of the current page, respectively.
471 However, if you change the variable @code{doc-view-continuous} to a
472 non-@code{nil} value, then @kbd{C-p} displays the previous page if you
473 are already at the beginning of the current page, and @kbd{C-n}
474 displays the next page if you are at the end of the current page.
476 @findex doc-view-next-page
477 @findex doc-view-previous-page
478 @kindex n @r{(DocView mode)}
479 @kindex p @r{(DocView mode)}
480 @kindex C-x ] @r{(DocView mode)}
481 @kindex C-x [ @r{(DocView mode)}
482 You can also display the next page by typing @kbd{n}, @key{next} or
483 @kbd{C-x ]} (@code{doc-view-next-page}). To display the previous
484 page, type @kbd{p}, @key{prior} or @kbd{C-x [}
485 (@code{doc-view-previous-page}).
487 @findex doc-view-scroll-up-or-next-page
488 @findex doc-view-scroll-down-or-previous-page
489 @kindex SPC @r{(DocView mode)}
490 @kindex DEL @r{(DocView mode)}
491 @key{SPC} (@code{doc-view-scroll-up-or-next-page}) is a convenient
492 way to advance through the document. It scrolls within the current
493 page or advances to the next. @key{DEL} moves backwards in a similar
494 way (@code{doc-view-scroll-down-or-previous-page}).
496 @findex doc-view-first-page
497 @findex doc-view-last-page
498 @findex doc-view-goto-page
499 @kindex M-< @r{(DocView mode)}
500 @kindex M-> @r{(DocView mode)}
501 To go to the first page, type @kbd{M-<}
502 (@code{doc-view-first-page}); to go to the last one, type @kbd{M->}
503 (@code{doc-view-last-page}). To jump to a page by its number, type
504 @kbd{M-g M-g} or @kbd{M-g g} (@code{doc-view-goto-page}).
506 @findex doc-view-enlarge
507 @findex doc-view-shrink
508 @vindex doc-view-resolution
509 @kindex + @r{(DocView mode)}
510 @kindex - @r{(DocView mode)}
511 You can enlarge or shrink the document with @kbd{+}
512 (@code{doc-view-enlarge}) and @kbd{-} (@code{doc-view-shrink}). These
513 commands work by reconverting the document at the new size. To
514 specify the default size for DocView, customize the variable
515 @code{doc-view-resolution}.
517 @node DocView Searching
518 @subsection DocView Searching
520 In DocView mode, you can search the file's text for a regular
521 expression (@pxref{Regexps}). The interface for searching is inspired
522 by @code{isearch} (@pxref{Incremental Search}).
524 @findex doc-view-search
525 @findex doc-view-search-backward
526 @findex doc-view-show-tooltip
527 To begin a search, type @kbd{C-s} (@code{doc-view-search}) or
528 @kbd{C-r} (@code{doc-view-search-backward}). This reads a regular
529 expression using a minibuffer, then echoes the number of matches found
530 within the document. You can move forward and back among the matches
531 by typing @kbd{C-s} and @kbd{C-r}. DocView mode has no way to show
532 the match inside the page image; instead, it displays a tooltip (at
533 the mouse position) listing all matching lines in the current page.
534 To force display of this tooltip, type @kbd{C-t}
535 (@code{doc-view-show-tooltip}).
537 To start a new search, use the search command with a prefix
538 argument; i.e., @kbd{C-u C-s} for a forward search or @kbd{C-u C-r}
539 for a backward search.
541 @node DocView Slicing
542 @subsection DocView Slicing
544 Documents often have wide margins for printing. They are annoying
545 when reading the document on the screen, because they use up screen
546 space and can cause inconvenient scrolling.
548 @findex doc-view-set-slice
549 @findex doc-view-set-slice-using-mouse
550 With DocView you can hide these margins by selecting a @dfn{slice}
551 of pages to display. A slice is a rectangle within the page area;
552 once you specify a slice in DocView, it applies to whichever page you
555 To specify the slice numerically, type @kbd{s s}
556 (@code{doc-view-set-slice}); then enter the top left pixel position
557 and the slice's width and height.
558 @c ??? how does this work?
560 A more convenient graphical way to specify the slice is with @kbd{s
561 m} (@code{doc-view-set-slice-using-mouse}), where you use the mouse to
562 select the slice. Simply press and hold the left mouse button at the
563 upper-left corner of the region you want to have in the slice, then
564 move the mouse pointer to the lower-right corner and release the
567 The most convenient way is to set the optimal slice by using
568 BoundingBox information automatically determined from the document by
569 typing @kbd{s b} (@code{doc-view-set-slice-from-bounding-box}).
571 @findex doc-view-reset-slice
572 To cancel the selected slice, type @kbd{s r}
573 (@code{doc-view-reset-slice}). Then DocView shows the entire page
574 including its entire margins.
576 @node DocView Conversion
577 @subsection DocView Conversion
579 @vindex doc-view-cache-directory
580 @findex doc-view-clear-cache
581 For efficiency, DocView caches the images produced by @command{gs}.
582 The name of this directory is given by the variable
583 @code{doc-view-cache-directory}. You can clear the cache directory by
584 typing @code{M-x doc-view-clear-cache}.
586 @findex doc-view-kill-proc
587 @findex doc-view-kill-proc-and-buffer
588 To force reconversion of the currently viewed document, type @kbd{r}
589 or @kbd{g} (@code{revert-buffer}). To kill the converter process
590 associated with the current buffer, type @kbd{K}
591 (@code{doc-view-kill-proc}). The command @kbd{k}
592 (@code{doc-view-kill-proc-and-buffer}) kills the converter process and
596 @section Web Browsing with EWW
599 @findex eww-open-file
600 @dfn{EWW}, the Emacs Web Wowser, is a web browser package for Emacs.
601 It allows browsing URLs within an Emacs buffer. The command @kbd{M-x
602 eww} will open a URL or search the web. You can open a file
603 using the command @kbd{M-x eww-open-file}. You can use EWW as the
604 web browser for @code{browse-url}, @pxref{Browse-URL}. For full
605 details, @pxref{Top, EWW,, eww, The Emacs Web Wowser Manual}.
607 @node Embedded WebKit Widgets
608 @section Embedded WebKit Widgets
610 @cindex webkit widgets
611 @cindex embedded widgets
613 @findex xwidget-webkit-browse-url
614 @findex xwidget-webkit-mode
615 @cindex Xwidget-WebKit mode
616 If Emacs was compiled with the appropriate support packages, it is
617 able to show browser widgets in its buffers. The command @kbd{M-x
618 xwidget-webkit-browse-url} asks for a URL to display in the browser
619 widget. The URL normally defaults to the URL at or before point, but
620 if there is an active region (@pxref{Mark}), the default URL comes
621 from the region instead, after removing any whitespace from it. The
622 command then creates a new buffer with the embedded browser showing
623 the specified URL. The buffer is put in the Xwidget-WebKit mode
624 (similar to Image mode, @pxref{File Conveniences}), which provides
625 one-key commands for scrolling the widget, changing its size, and
626 reloading it. Type @w{@kbd{C-h b}} in that buffer to see the key
630 @section Running Shell Commands from Emacs
632 @cindex shell commands
634 Emacs has commands for passing single command lines to shell
635 subprocesses, and for running a shell interactively with input and
636 output to an Emacs buffer, and for running a shell in a terminal
640 @item M-! @var{cmd} @key{RET}
641 Run the shell command @var{cmd} and display the output
642 (@code{shell-command}).
643 @item M-| @var{cmd} @key{RET}
644 Run the shell command @var{cmd} with region contents as input;
645 optionally replace the region with the output
646 (@code{shell-command-on-region}).
647 @item M-& @var{cmd} @key{RET}
648 Run the shell command @var{cmd} asynchronously, and display the output
649 (@code{async-shell-command}).
651 Run a subshell with input and output through an Emacs buffer. You can
652 then give commands interactively.
654 Run a subshell with input and output through an Emacs buffer. You can
655 then give commands interactively. Full terminal emulation is
660 Whenever you specify a relative file name for an executable program
661 (either in the @var{cmd} argument to one of the above commands, or in
662 other contexts), Emacs searches for the program in the directories
663 specified by the variable @code{exec-path}. The value of this
664 variable must be a list of directory names; the default value is
665 initialized from the environment variable @env{PATH} when Emacs is
666 started (@pxref{General Variables}).
668 @kbd{M-x eshell} invokes a shell implemented entirely in Emacs. It
669 is documented in its own manual.
671 @xref{Top,Eshell,Eshell, eshell, Eshell: The Emacs Shell}.
674 See the Eshell Info manual, which is distributed with Emacs.
678 * Single Shell:: How to run one shell command and return.
679 * Interactive Shell:: Permanent shell taking input via Emacs.
680 * Shell Mode:: Special Emacs commands used with permanent shell.
681 * Shell Prompts:: Two ways to recognize shell prompts.
682 * History: Shell History. Repeating previous commands in a shell buffer.
683 * Directory Tracking:: Keeping track when the subshell changes directory.
684 * Options: Shell Options. Options for customizing Shell mode.
685 * Terminal emulator:: An Emacs window as a terminal emulator.
686 * Term Mode:: Special Emacs commands used in Term mode.
687 * Remote Host:: Connecting to another computer.
688 * Serial Terminal:: Connecting to a serial port.
692 @subsection Single Shell Commands
695 @findex shell-command
696 @kbd{M-!} (@code{shell-command}) reads a line of text using the
697 minibuffer and executes it as a shell command, in a subshell made just
698 for that command. Standard input for the command comes from the null
699 device. If the shell command produces any output, the output appears
700 either in the echo area (if it is short), or in an Emacs buffer named
701 @file{*Shell Command Output*}, displayed in another window (if the
704 For instance, one way to decompress a file named @file{foo.gz} is to
705 type @kbd{M-! gunzip foo.gz @key{RET}}. That shell command normally
706 creates the file @file{foo} and produces no terminal output.
708 A numeric argument to @code{shell-command}, e.g., @kbd{M-1 M-!},
709 causes it to insert terminal output into the current buffer instead of
710 a separate buffer. It puts point before the output, and sets the mark
711 after the output. For instance, @kbd{M-1 M-! gunzip < foo.gz
712 @key{RET}} would insert the uncompressed form of the file
713 @file{foo.gz} into the current buffer.
715 Provided the specified shell command does not end with @samp{&}, it
716 runs @dfn{synchronously}, and you must wait for it to exit before
717 continuing to use Emacs. To stop waiting, type @kbd{C-g} to quit;
718 this sends a @code{SIGINT} signal to terminate the shell command (this
719 is the same signal that @kbd{C-c} normally generates in the shell).
720 Emacs then waits until the command actually terminates. If the shell
721 command doesn't stop (because it ignores the @code{SIGINT} signal),
722 type @kbd{C-g} again; this sends the command a @code{SIGKILL} signal,
723 which is impossible to ignore.
726 @findex async-shell-command
727 A shell command that ends in @samp{&} is executed
728 @dfn{asynchronously}, and you can continue to use Emacs as it runs.
729 You can also type @kbd{M-&} (@code{async-shell-command}) to execute a
730 shell command asynchronously; this is exactly like calling @kbd{M-!}
731 with a trailing @samp{&}, except that you do not need the @samp{&}.
732 The default output buffer for asynchronous shell commands is named
733 @samp{*Async Shell Command*}. Emacs inserts the output into this
734 buffer as it comes in, whether or not the buffer is visible in a
737 @vindex async-shell-command-buffer
738 If you want to run more than one asynchronous shell command at the
739 same time, they could end up competing for the output buffer. The
740 option @code{async-shell-command-buffer} specifies what to do about
741 this; e.g., whether to rename the pre-existing output buffer, or to
742 use a different buffer for the new command. Consult the variable's
743 documentation for more possibilities.
746 @findex shell-command-on-region
747 @kbd{M-|} (@code{shell-command-on-region}) is like @kbd{M-!}, but
748 passes the contents of the region as the standard input to the shell
749 command, instead of no input. With a numeric argument, it deletes the
750 old region and replaces it with the output from the shell command.
752 For example, you can use @kbd{M-|} with the @command{gpg} program to
753 see what keys are in the buffer. If the buffer contains a GnuPG key,
754 type @kbd{C-x h M-| gpg @key{RET}} to feed the entire buffer contents
755 to @command{gpg}. This will output the list of keys to the
756 @file{*Shell Command Output*} buffer.
758 @vindex shell-file-name
759 The above commands use the shell specified by the variable
760 @code{shell-file-name}. Its default value is determined by the
761 @env{SHELL} environment variable when Emacs is started. If the file
762 name is relative, Emacs searches the directories listed in
763 @code{exec-path} (@pxref{Shell}).
765 To specify a coding system for @kbd{M-!} or @kbd{M-|}, use the command
766 @kbd{C-x @key{RET} c} immediately beforehand. @xref{Communication Coding}.
768 @vindex shell-command-default-error-buffer
769 By default, error output is intermixed with the regular output in
770 the output buffer. But if you change the value of the variable
771 @code{shell-command-default-error-buffer} to a string, error output is
772 inserted into a buffer of that name.
774 @node Interactive Shell
775 @subsection Interactive Subshell
778 To run a subshell interactively, type @kbd{M-x shell}. This creates
779 (or reuses) a buffer named @file{*shell*}, and runs a shell subprocess
780 with input coming from and output going to that buffer. That is to
781 say, any terminal output from the subshell goes into the buffer,
782 advancing point, and any terminal input for the subshell comes from
783 text in the buffer. To give input to the subshell, go to the end of
784 the buffer and type the input, terminated by @key{RET}.
786 By default, when the subshell is invoked interactively, the
787 @file{*shell*} buffer is displayed in a new window. This behavior can
788 be customized via @code{display-buffer-alist} (@pxref{Window Choice}).
790 While the subshell is waiting or running a command, you can switch
791 windows or buffers and perform other editing in Emacs. Emacs inserts
792 the output from the subshell into the Shell buffer whenever it has
793 time to process it (e.g., while waiting for keyboard input).
795 @cindex @code{comint-highlight-input} face
796 @cindex @code{comint-highlight-prompt} face
797 In the Shell buffer, prompts are displayed with the face
798 @code{comint-highlight-prompt}, and submitted input lines are
799 displayed with the face @code{comint-highlight-input}. This makes it
800 easier to distinguish input lines from the shell output.
803 To make multiple subshells, invoke @kbd{M-x shell} with a prefix
804 argument (e.g., @kbd{C-u M-x shell}). Then the command will read a
805 buffer name, and create (or reuse) a subshell in that buffer. You can
806 also rename the @file{*shell*} buffer using @kbd{M-x rename-uniquely},
807 then create a new @file{*shell*} buffer using plain @kbd{M-x shell}.
808 Subshells in different buffers run independently and in parallel.
810 @vindex explicit-shell-file-name
811 @cindex environment variables for subshells
812 @cindex @env{ESHELL} environment variable
813 @cindex @env{SHELL} environment variable
814 To specify the shell file name used by @kbd{M-x shell}, customize
815 the variable @code{explicit-shell-file-name}. If this is @code{nil}
816 (the default), Emacs uses the environment variable @env{ESHELL} if it
817 exists. Otherwise, it usually uses the variable
818 @code{shell-file-name} (@pxref{Single Shell}); but if the default
819 directory is remote (@pxref{Remote Files}), it prompts you for the
822 Emacs sends the new shell the contents of the file
823 @file{~/.emacs_@var{shellname}} as input, if it exists, where
824 @var{shellname} is the name of the file that the shell was loaded
825 from. For example, if you use bash, the file sent to it is
826 @file{~/.emacs_bash}. If this file is not found, Emacs tries with
827 @file{~/.emacs.d/init_@var{shellname}.sh}.
829 To specify a coding system for the shell, you can use the command
830 @kbd{C-x @key{RET} c} immediately before @kbd{M-x shell}. You can
831 also change the coding system for a running subshell by typing
832 @kbd{C-x @key{RET} p} in the shell buffer. @xref{Communication
835 @cindex @env{INSIDE_EMACS} environment variable
836 Emacs sets the environment variable @env{INSIDE_EMACS} in the
837 subshell to @samp{@var{version},comint}, where @var{version} is the
838 Emacs version (e.g., @samp{24.1}). Programs can check this variable
839 to determine whether they are running inside an Emacs subshell.
842 @subsection Shell Mode
846 The major mode for Shell buffers is Shell mode. Many of its special
847 commands are bound to the @kbd{C-c} prefix, and resemble the usual
848 editing and job control characters present in ordinary shells, except
849 that you must type @kbd{C-c} first. Here is a list of Shell mode
854 @kindex RET @r{(Shell mode)}
855 @findex comint-send-input
856 Send the current line as input to the subshell
857 (@code{comint-send-input}). Any shell prompt at the beginning of the
858 line is omitted (@pxref{Shell Prompts}). If point is at the end of
859 buffer, this is like submitting the command line in an ordinary
860 interactive shell. However, you can also invoke @key{RET} elsewhere
861 in the shell buffer to submit the current line as input.
864 @kindex TAB @r{(Shell mode)}
865 @findex completion-at-point
866 @cindex shell completion
867 Complete the command name or file name before point in the shell
868 buffer (@code{completion-at-point}). This uses the usual Emacs
869 completion rules (@pxref{Completion}), with the completion
870 alternatives being file names, environment variable names, the shell
871 command history, and history references (@pxref{History References}).
872 For options controlling the completion, @pxref{Shell Options}.
875 @kindex M-? @r{(Shell mode)}
876 @findex comint-dynamic-list-filename@dots{}
877 Display temporarily a list of the possible completions of the file
878 name before point (@code{comint-dynamic-list-filename-completions}).
881 @kindex C-d @r{(Shell mode)}
882 @findex comint-delchar-or-maybe-eof
883 Either delete a character or send @acronym{EOF}
884 (@code{comint-delchar-or-maybe-eof}). Typed at the end of the shell
885 buffer, this sends @acronym{EOF} to the subshell. Typed at any other
886 position in the buffer, this deletes a character as usual.
889 @kindex C-c C-a @r{(Shell mode)}
890 @findex comint-bol-or-process-mark
891 Move to the beginning of the line, but after the prompt if any
892 (@code{comint-bol-or-process-mark}). If you repeat this command twice
893 in a row, the second time it moves back to the process mark, which is
894 the beginning of the input that you have not yet sent to the subshell.
895 (Normally that is the same place---the end of the prompt on this
896 line---but after @kbd{C-c @key{SPC}} the process mark may be in a
900 Accumulate multiple lines of input, then send them together. This
901 command inserts a newline before point, but does not send the preceding
902 text as input to the subshell---at least, not yet. Both lines, the one
903 before this newline and the one after, will be sent together (along with
904 the newline that separates them), when you type @key{RET}.
907 @kindex C-c C-u @r{(Shell mode)}
908 @findex comint-kill-input
909 Kill all text pending at end of buffer to be sent as input
910 (@code{comint-kill-input}). If point is not at end of buffer,
911 this only kills the part of this text that precedes point.
914 @kindex C-c C-w @r{(Shell mode)}
915 Kill a word before point (@code{backward-kill-word}).
918 @kindex C-c C-c @r{(Shell mode)}
919 @findex comint-interrupt-subjob
920 Interrupt the shell or its current subjob if any
921 (@code{comint-interrupt-subjob}). This command also kills
922 any shell input pending in the shell buffer and not yet sent.
925 @kindex C-c C-z @r{(Shell mode)}
926 @findex comint-stop-subjob
927 Stop the shell or its current subjob if any (@code{comint-stop-subjob}).
928 This command also kills any shell input pending in the shell buffer and
932 @findex comint-quit-subjob
933 @kindex C-c C-\ @r{(Shell mode)}
934 Send quit signal to the shell or its current subjob if any
935 (@code{comint-quit-subjob}). This command also kills any shell input
936 pending in the shell buffer and not yet sent.
939 @kindex C-c C-o @r{(Shell mode)}
940 @findex comint-delete-output
941 Delete the last batch of output from a shell command
942 (@code{comint-delete-output}). This is useful if a shell command spews
943 out lots of output that just gets in the way.
946 @kindex C-c C-s @r{(Shell mode)}
947 @findex comint-write-output
948 Write the last batch of output from a shell command to a file
949 (@code{comint-write-output}). With a prefix argument, the file is
950 appended to instead. Any prompt at the end of the output is not
955 @kindex C-c C-r @r{(Shell mode)}
956 @kindex C-M-l @r{(Shell mode)}
957 @findex comint-show-output
958 Scroll to display the beginning of the last batch of output at the top
959 of the window; also move the cursor there (@code{comint-show-output}).
962 @kindex C-c C-e @r{(Shell mode)}
963 @findex comint-show-maximum-output
964 Scroll to put the end of the buffer at the bottom of the window
965 (@code{comint-show-maximum-output}).
968 @kindex C-c C-f @r{(Shell mode)}
969 @findex shell-forward-command
970 @vindex shell-command-regexp
971 Move forward across one shell command, but not beyond the current line
972 (@code{shell-forward-command}). The variable @code{shell-command-regexp}
973 specifies how to recognize the end of a command.
976 @kindex C-c C-b @r{(Shell mode)}
977 @findex shell-backward-command
978 Move backward across one shell command, but not beyond the current line
979 (@code{shell-backward-command}).
982 Ask the shell for its working directory, and update the Shell buffer's
983 default directory. @xref{Directory Tracking}.
985 @item M-x send-invisible @key{RET} @var{text} @key{RET}
986 @findex send-invisible
987 Send @var{text} as input to the shell, after reading it without
988 echoing. This is useful when a shell command runs a program that asks
991 Please note that Emacs will not echo passwords by default. If you
992 really want them to be echoed, evaluate (@pxref{Lisp Eval}) the
993 following Lisp expression:
996 (remove-hook 'comint-output-filter-functions
997 'comint-watch-for-password-prompt)
1000 @item M-x comint-continue-subjob
1001 @findex comint-continue-subjob
1002 Continue the shell process. This is useful if you accidentally suspend
1003 the shell process.@footnote{You should not suspend the shell process.
1004 Suspending a subjob of the shell is a completely different matter---that
1005 is normal practice, but you must use the shell to continue the subjob;
1006 this command won't do it.}
1008 @item M-x comint-strip-ctrl-m
1009 @findex comint-strip-ctrl-m
1010 Discard all control-M characters from the current group of shell output.
1011 The most convenient way to use this command is to make it run
1012 automatically when you get output from the subshell. To do that,
1013 evaluate this Lisp expression:
1016 (add-hook 'comint-output-filter-functions
1017 'comint-strip-ctrl-m)
1020 @item M-x comint-truncate-buffer
1021 @findex comint-truncate-buffer
1022 This command truncates the shell buffer to a certain maximum number of
1023 lines, specified by the variable @code{comint-buffer-maximum-size}.
1024 Here's how to do this automatically each time you get output from the
1028 (add-hook 'comint-output-filter-functions
1029 'comint-truncate-buffer)
1034 @cindex mode, Comint
1035 Shell mode is a derivative of Comint mode, a general-purpose mode for
1036 communicating with interactive subprocesses. Most of the features of
1037 Shell mode actually come from Comint mode, as you can see from the
1038 command names listed above. The special features of Shell mode include
1039 the directory tracking feature, and a few user commands.
1041 Other Emacs features that use variants of Comint mode include GUD
1042 (@pxref{Debuggers}) and @kbd{M-x run-lisp} (@pxref{External Lisp}).
1045 You can use @kbd{M-x comint-run} to execute any program of your choice
1046 in a subprocess using unmodified Comint mode---without the
1047 specializations of Shell mode.
1050 @subsection Shell Prompts
1052 @cindex prompt, shell
1053 A prompt is text output by a program to show that it is ready to
1054 accept new user input. Normally, Comint mode (and thus Shell mode)
1055 automatically figures out part of the buffer is a prompt, based on the
1056 output of the subprocess. (Specifically, it assumes that any received
1057 output line which doesn't end with a newline is a prompt.)
1059 Comint mode divides the buffer into two types of @dfn{fields}: input
1060 fields (where user input is typed) and output fields (everywhere
1061 else). Prompts are part of the output fields. Most Emacs motion
1062 commands do not cross field boundaries, unless they move over multiple
1063 lines. For instance, when point is in the input field on a shell
1064 command line, @kbd{C-a} puts point at the beginning of the input
1065 field, after the prompt. Internally, the fields are implemented using
1066 the @code{field} text property (@pxref{Text Properties,,, elisp, the
1067 Emacs Lisp Reference Manual}).
1069 @vindex comint-use-prompt-regexp
1070 @vindex shell-prompt-pattern
1071 If you change the variable @code{comint-use-prompt-regexp} to a
1072 non-@code{nil} value, then Comint mode recognize prompts using a
1073 regular expression (@pxref{Regexps}). In Shell mode, the regular
1074 expression is specified by the variable @code{shell-prompt-pattern}.
1075 The default value of @code{comint-use-prompt-regexp} is @code{nil},
1076 because this method for recognizing prompts is unreliable, but you may
1077 want to set it to a non-@code{nil} value in unusual circumstances. In
1078 that case, Emacs does not divide the Comint buffer into fields, so the
1079 general motion commands behave as they normally do in buffers without
1080 special text properties. However, you can use the paragraph motion
1081 commands to conveniently navigate the buffer (@pxref{Paragraphs}); in
1082 Shell mode, Emacs uses @code{shell-prompt-pattern} as paragraph
1086 @subsection Shell Command History
1088 Shell buffers support three ways of repeating earlier commands. You
1089 can use keys like those used for the minibuffer history; these work
1090 much as they do in the minibuffer, inserting text from prior commands
1091 while point remains always at the end of the buffer. You can move
1092 through the buffer to previous inputs in their original place, then
1093 resubmit them or copy them to the end. Or you can use a
1094 @samp{!}-style history reference.
1097 * Ring: Shell Ring. Fetching commands from the history list.
1098 * Copy: Shell History Copying. Moving to a command and then copying it.
1099 * History References:: Expanding @samp{!}-style history references.
1103 @subsubsection Shell History Ring
1106 @findex comint-previous-input
1107 @kindex M-p @r{(Shell mode)}
1110 Fetch the next earlier old shell command.
1112 @kindex M-n @r{(Shell mode)}
1113 @findex comint-next-input
1116 Fetch the next later old shell command.
1118 @kindex M-r @r{(Shell mode)}
1119 @findex comint-history-isearch-backward-regexp
1121 Begin an incremental regexp search of old shell commands.
1124 @kindex C-c C-x @r{(Shell mode)}
1125 @findex comint-get-next-from-history
1126 Fetch the next subsequent command from the history.
1129 @kindex C-c . @r{(Shell mode)}
1130 @findex comint-input-previous-argument
1131 Fetch one argument from an old shell command.
1134 @kindex C-c C-l @r{(Shell mode)}
1135 @findex comint-dynamic-list-input-ring
1136 Display the buffer's history of shell commands in another window
1137 (@code{comint-dynamic-list-input-ring}).
1140 Shell buffers provide a history of previously entered shell
1141 commands. To reuse shell commands from the history, use the editing
1142 commands @kbd{M-p}, @kbd{M-n}, @kbd{M-r} and @kbd{M-s}. These work
1143 just like the minibuffer history commands (@pxref{Minibuffer
1144 History}), except that they operate within the Shell buffer rather
1145 than the minibuffer.
1147 @kbd{M-p} fetches an earlier shell command to the end of the shell
1148 buffer. Successive use of @kbd{M-p} fetches successively earlier
1149 shell commands, each replacing any text that was already present as
1150 potential shell input. @kbd{M-n} does likewise except that it finds
1151 successively more recent shell commands from the buffer.
1152 @kbd{C-@key{UP}} works like @kbd{M-p}, and @kbd{C-@key{DOWN}} like
1155 The history search command @kbd{M-r} begins an incremental regular
1156 expression search of previous shell commands. After typing @kbd{M-r},
1157 start typing the desired string or regular expression; the last
1158 matching shell command will be displayed in the current line.
1159 Incremental search commands have their usual effects---for instance,
1160 @kbd{C-s} and @kbd{C-r} search forward and backward for the next match
1161 (@pxref{Incremental Search}). When you find the desired input, type
1162 @key{RET} to terminate the search. This puts the input in the command
1163 line. Any partial input you were composing before navigating the
1164 history list is restored when you go to the beginning or end of the
1167 Often it is useful to reexecute several successive shell commands that
1168 were previously executed in sequence. To do this, first find and
1169 reexecute the first command of the sequence. Then type @kbd{C-c C-x};
1170 that will fetch the following command---the one that follows the command
1171 you just repeated. Then type @key{RET} to reexecute this command. You
1172 can reexecute several successive commands by typing @kbd{C-c C-x
1173 @key{RET}} over and over.
1175 The command @kbd{C-c .}@: (@code{comint-input-previous-argument})
1176 copies an individual argument from a previous command, like
1177 @kbd{@key{ESC} .} in Bash. The simplest use copies the last argument from the
1178 previous shell command. With a prefix argument @var{n}, it copies the
1179 @var{n}th argument instead. Repeating @kbd{C-c .} copies from an
1180 earlier shell command instead, always using the same value of @var{n}
1181 (don't give a prefix argument when you repeat the @kbd{C-c .}
1184 These commands get the text of previous shell commands from a special
1185 history list, not from the shell buffer itself. Thus, editing the shell
1186 buffer, or even killing large parts of it, does not affect the history
1187 that these commands access.
1189 @vindex shell-input-ring-file-name
1190 Some shells store their command histories in files so that you can
1191 refer to commands from previous shell sessions. Emacs reads
1192 the command history file for your chosen shell, to initialize its own
1193 command history. The file name is @file{~/.bash_history} for bash,
1194 @file{~/.sh_history} for ksh, and @file{~/.history} for other shells.
1196 @node Shell History Copying
1197 @subsubsection Shell History Copying
1200 @kindex C-c C-p @r{(Shell mode)}
1201 @findex comint-previous-prompt
1203 Move point to the previous prompt (@code{comint-previous-prompt}).
1205 @kindex C-c C-n @r{(Shell mode)}
1206 @findex comint-next-prompt
1208 Move point to the following prompt (@code{comint-next-prompt}).
1210 @kindex C-c RET @r{(Shell mode)}
1211 @findex comint-copy-old-input
1213 Copy the input command at point, inserting the copy at the end of the
1214 buffer (@code{comint-copy-old-input}). This is useful if you move
1215 point back to a previous command. After you copy the command, you can
1216 submit the copy as input with @key{RET}. If you wish, you can edit
1217 the copy before resubmitting it. If you use this command on an output
1218 line, it copies that line to the end of the buffer.
1221 If @code{comint-use-prompt-regexp} is @code{nil} (the default), copy
1222 the old input command that you click on, inserting the copy at the end
1223 of the buffer (@code{comint-insert-input}). If
1224 @code{comint-use-prompt-regexp} is non-@code{nil}, or if the click is
1225 not over old input, just yank as usual.
1228 Moving to a previous input and then copying it with @kbd{C-c
1229 @key{RET}} or @kbd{Mouse-2} produces the same results---the same
1230 buffer contents---that you would get by using @kbd{M-p} enough times
1231 to fetch that previous input from the history list. However, @kbd{C-c
1232 @key{RET}} copies the text from the buffer, which can be different
1233 from what is in the history list if you edit the input text in the
1234 buffer after it has been sent.
1236 @node History References
1237 @subsubsection Shell History References
1238 @cindex history reference
1240 Various shells including csh and bash support @dfn{history
1241 references} that begin with @samp{!} and @samp{^}. Shell mode
1242 recognizes these constructs, and can perform the history substitution
1245 If you insert a history reference and type @key{TAB}, this searches
1246 the input history for a matching command, performs substitution if
1247 necessary, and places the result in the buffer in place of the history
1248 reference. For example, you can fetch the most recent command
1249 beginning with @samp{mv} with @kbd{! m v @key{TAB}}. You can edit the
1250 command if you wish, and then resubmit the command to the shell by
1253 @vindex comint-input-autoexpand
1254 @findex comint-magic-space
1255 Shell mode can optionally expand history references in the buffer
1256 when you send them to the shell. To request this, set the variable
1257 @code{comint-input-autoexpand} to @code{input}. You can make
1258 @key{SPC} perform history expansion by binding @key{SPC} to the
1259 command @code{comint-magic-space}.
1261 Shell mode recognizes history references when they follow a prompt.
1262 @xref{Shell Prompts}, for how Shell mode recognizes prompts.
1264 @node Directory Tracking
1265 @subsection Directory Tracking
1266 @cindex directory tracking
1268 @vindex shell-pushd-regexp
1269 @vindex shell-popd-regexp
1270 @vindex shell-cd-regexp
1271 Shell mode keeps track of @samp{cd}, @samp{pushd} and @samp{popd}
1272 commands given to the subshell, in order to keep the Shell buffer's
1273 default directory (@pxref{File Names}) the same as the shell's working
1274 directory. It recognizes these commands by examining lines of input
1277 If you use aliases for these commands, you can tell Emacs to
1278 recognize them also, by setting the variables
1279 @code{shell-pushd-regexp}, @code{shell-popd-regexp}, and
1280 @code{shell-cd-regexp} to the appropriate regular expressions
1281 (@pxref{Regexps}). For example, if @code{shell-pushd-regexp} matches
1282 the beginning of a shell command line, that line is regarded as a
1283 @code{pushd} command. These commands are recognized only at the
1284 beginning of a shell command line.
1287 If Emacs gets confused about changes in the working directory of the
1288 subshell, type @kbd{M-x dirs}. This command asks the shell for its
1289 working directory and updates the default directory accordingly. It
1290 works for shells that support the most common command syntax, but may
1291 not work for unusual shells.
1293 @findex dirtrack-mode
1294 @cindex Dirtrack mode
1295 @cindex mode, Dirtrack
1296 @vindex dirtrack-list
1297 You can also use Dirtrack mode, a buffer-local minor mode that
1298 implements an alternative method of tracking the shell's working
1299 directory. To use this method, your shell prompt must contain the
1300 working directory at all times, and you must supply a regular
1301 expression for recognizing which part of the prompt contains the
1302 working directory; see the documentation of the variable
1303 @code{dirtrack-list} for details. To use Dirtrack mode, type @kbd{M-x
1304 dirtrack-mode} in the Shell buffer, or add @code{dirtrack-mode} to
1305 @code{shell-mode-hook} (@pxref{Hooks}).
1308 @subsection Shell Mode Options
1310 @vindex comint-scroll-to-bottom-on-input
1311 If the variable @code{comint-scroll-to-bottom-on-input} is
1312 non-@code{nil}, insertion and yank commands scroll the selected window
1313 to the bottom before inserting. The default is @code{nil}.
1315 @vindex comint-scroll-show-maximum-output
1316 If @code{comint-scroll-show-maximum-output} is non-@code{nil}, then
1317 arrival of output when point is at the end tries to scroll the last
1318 line of text to the bottom line of the window, showing as much useful
1319 text as possible. (This mimics the scrolling behavior of most
1320 terminals.) The default is @code{t}.
1322 @vindex comint-move-point-for-output
1323 By setting @code{comint-move-point-for-output}, you can opt for
1324 having point jump to the end of the buffer whenever output arrives---no
1325 matter where in the buffer point was before. If the value is
1326 @code{this}, point jumps in the selected window. If the value is
1327 @code{all}, point jumps in each window that shows the Comint buffer. If
1328 the value is @code{other}, point jumps in all nonselected windows that
1329 show the current buffer. The default value is @code{nil}, which means
1330 point does not jump to the end.
1332 @vindex comint-prompt-read-only
1333 If you set @code{comint-prompt-read-only}, the prompts in the Comint
1334 buffer are read-only.
1336 @vindex comint-input-ignoredups
1337 The variable @code{comint-input-ignoredups} controls whether successive
1338 identical inputs are stored in the input history. A non-@code{nil}
1339 value means to omit an input that is the same as the previous input.
1340 The default is @code{nil}, which means to store each input even if it is
1341 equal to the previous input.
1343 @vindex comint-completion-addsuffix
1344 @vindex comint-completion-recexact
1345 @vindex comint-completion-autolist
1346 Three variables customize file name completion. The variable
1347 @code{comint-completion-addsuffix} controls whether completion inserts a
1348 space or a slash to indicate a fully completed file or directory name
1349 (non-@code{nil} means do insert a space or slash).
1350 @code{comint-completion-recexact}, if non-@code{nil}, directs @key{TAB}
1351 to choose the shortest possible completion if the usual Emacs completion
1352 algorithm cannot add even a single character.
1353 @code{comint-completion-autolist}, if non-@code{nil}, says to list all
1354 the possible completions whenever completion is not exact.
1356 @vindex shell-completion-execonly
1357 Command completion normally considers only executable files.
1358 If you set @code{shell-completion-execonly} to @code{nil},
1359 it considers nonexecutable files as well.
1361 @vindex shell-completion-fignore
1362 @vindex comint-completion-fignore
1363 The variable @code{shell-completion-fignore} specifies a list of file
1364 name extensions to ignore in Shell mode completion. The default
1365 setting is @code{nil}, but some users prefer @code{("~" "#" "%")} to
1366 ignore file names ending in @samp{~}, @samp{#} or @samp{%}. Other
1367 related Comint modes use the variable @code{comint-completion-fignore}
1370 @findex shell-dynamic-complete-command
1371 Some implementation details of the shell command completion may also be found
1372 in the lisp documentation of the @code{shell-dynamic-complete-command}
1375 @findex shell-pushd-tohome
1376 @findex shell-pushd-dextract
1377 @findex shell-pushd-dunique
1378 You can configure the behavior of @samp{pushd}. Variables control
1379 whether @samp{pushd} behaves like @samp{cd} if no argument is given
1380 (@code{shell-pushd-tohome}), pop rather than rotate with a numeric
1381 argument (@code{shell-pushd-dextract}), and only add directories to the
1382 directory stack if they are not already on it
1383 (@code{shell-pushd-dunique}). The values you choose should match the
1384 underlying shell, of course.
1386 @node Terminal emulator
1387 @subsection Emacs Terminal Emulator
1390 To run a subshell in a text terminal emulator, use @kbd{M-x term}.
1391 This creates (or reuses) a buffer named @file{*terminal*}, and runs a
1392 subshell with input coming from your keyboard, and output going to
1395 @cindex line mode @r{(terminal emulator)}
1396 @cindex char mode @r{(terminal emulator)}
1397 The terminal emulator uses Term mode, which has two input modes. In
1398 @dfn{line mode}, Term basically acts like Shell mode (@pxref{Shell
1399 Mode}). In @dfn{char mode}, each character is sent directly to the
1400 subshell, as terminal input; the sole exception is the terminal escape
1401 character, which by default is @kbd{C-c} (@pxref{Term Mode}). Any
1402 echoing of your input is the responsibility of the subshell; any
1403 terminal output from the subshell goes into the buffer, advancing
1406 Some programs (such as Emacs itself) need to control the appearance
1407 of the terminal screen in detail. They do this by emitting special
1408 control codes. Term mode recognizes and handles ANSI-standard
1409 VT100-style escape sequences, which are accepted by most modern
1410 terminals, including @command{xterm}. (Hence, you can actually run
1411 Emacs inside an Emacs Term window.)
1413 The @code{term} face specifies the default appearance of text
1414 in the terminal emulator (the default is the same appearance as the
1415 @code{default} face). When terminal control codes are used to change
1416 the appearance of text, these are represented in the terminal emulator
1417 by the faces @code{term-color-black}, @code{term-color-red},
1418 @code{term-color-green}, @code{term-color-yellow}
1419 @code{term-color-blue}, @code{term-color-magenta},
1420 @code{term-color-cyan}, @code{term-color-white},
1421 @code{term-color-underline}, and @code{term-color-bold}.
1424 You can also Term mode to communicate with a device connected to a
1425 serial port. @xref{Serial Terminal}.
1427 The file name used to load the subshell is determined the same way
1428 as for Shell mode. To make multiple terminal emulators, rename the
1429 buffer @file{*terminal*} to something different using @kbd{M-x
1430 rename-uniquely}, just as with Shell mode.
1432 Unlike Shell mode, Term mode does not track the current directory by
1433 examining your input. But some shells can tell Term what the current
1434 directory is. This is done automatically by @code{bash} version 1.15
1441 @subsection Term Mode
1445 The terminal emulator uses Term mode, which has two input modes. In
1446 line mode, Term basically acts like Shell mode (@pxref{Shell Mode}).
1447 In char mode, each character is sent directly to the subshell, except
1448 for the Term escape character, normally @kbd{C-c}.
1450 To switch between line and char mode, use these commands:
1453 @kindex C-c C-j @r{(Term mode)}
1454 @findex term-line-mode
1456 Switch to line mode (@code{term-line-mode}). Do nothing if already in
1459 @kindex C-c C-k @r{(Term mode)}
1460 @findex term-char-mode
1462 Switch to char mode (@code{term-char-mode}). Do nothing if already in
1466 The following commands are only available in char mode:
1470 Send a literal @kbd{C-c} to the sub-shell.
1472 @item C-c @var{char}
1473 This is equivalent to @kbd{C-x @var{char}} in normal Emacs. For
1474 example, @kbd{C-c o} invokes the global binding of @kbd{C-x o}, which
1475 is normally @samp{other-window}.
1478 @cindex paging in Term mode
1479 Term mode has a page-at-a-time feature. When enabled, it makes
1480 output pause at the end of each screenful:
1483 @kindex C-c C-q @r{(Term mode)}
1484 @findex term-pager-toggle
1486 Toggle the page-at-a-time feature. This command works in both line
1487 and char modes. When the feature is enabled, the mode-line displays
1488 the word @samp{page}, and each time Term receives more than a
1489 screenful of output, it pauses and displays @samp{**MORE**} in the
1490 mode-line. Type @key{SPC} to display the next screenful of output, or
1491 @kbd{?} to see your other options. The interface is similar to the
1492 @code{more} program.
1496 @subsection Remote Host Shell
1498 @cindex connecting to remote host
1502 You can login to a remote computer, using whatever commands you
1503 would from a regular terminal (e.g., using the @code{telnet} or
1504 @code{rlogin} commands), from a Term window.
1506 A program that asks you for a password will normally suppress
1507 echoing of the password, so the password will not show up in the
1508 buffer. This will happen just as if you were using a real terminal,
1509 if the buffer is in char mode. If it is in line mode, the password is
1510 temporarily visible, but will be erased when you hit return. (This
1511 happens automatically; there is no special password processing.)
1513 When you log in to a different machine, you need to specify the type
1514 of terminal you're using, by setting the @env{TERM} environment
1515 variable in the environment for the remote login command. (If you use
1516 bash, you do that by writing the variable assignment before the remote
1517 login command, without a separating comma.) Terminal types
1518 @samp{ansi} or @samp{vt100} will work on most systems.
1520 @node Serial Terminal
1521 @subsection Serial Terminal
1522 @cindex terminal, serial
1525 If you have a device connected to a serial port of your computer,
1526 you can communicate with it by typing @kbd{M-x serial-term}. This
1527 command asks for a serial port name and speed, and switches to a new
1528 Term mode buffer. Emacs communicates with the serial device through
1529 this buffer just like it does with a terminal in ordinary Term mode.
1531 The speed of the serial port is measured in bits per second. The
1532 most common speed is 9600 bits per second. You can change the speed
1533 interactively by clicking on the mode line.
1535 A serial port can be configured even more by clicking on @samp{8N1} in
1536 the mode line. By default, a serial port is configured as @samp{8N1},
1537 which means that each byte consists of 8 data bits, No parity check
1540 If the speed or the configuration is wrong, you cannot communicate
1541 with your device and will probably only see garbage output in the
1545 @section Using Emacs as a Server
1547 @cindex Emacs as a server
1548 @cindex server, using Emacs as
1549 @cindex @env{EDITOR} environment variable
1551 Various programs can invoke your choice of editor to edit a
1552 particular piece of text. For instance, version control programs
1553 invoke an editor to enter version control logs (@pxref{Version
1554 Control}), and the Unix @command{mail} utility invokes an editor to
1555 enter a message to send. By convention, your choice of editor is
1556 specified by the environment variable @env{EDITOR}. If you set
1557 @env{EDITOR} to @samp{emacs}, Emacs would be invoked, but in an
1558 inconvenient way---by starting a new Emacs process. This is
1559 inconvenient because the new Emacs process doesn't share buffers, a
1560 command history, or other kinds of information with any existing Emacs
1563 You can solve this problem by setting up Emacs as an @dfn{edit
1564 server}, so that it ``listens'' for external edit requests and acts
1565 accordingly. There are two ways to start an Emacs server:
1568 @findex server-start
1570 Run the command @code{server-start} in an existing Emacs process:
1571 either type @kbd{M-x server-start}, or put the expression
1572 @code{(server-start)} in your init file (@pxref{Init File}). The
1573 existing Emacs process is the server; when you exit Emacs, the server
1574 dies with the Emacs process.
1576 @cindex daemon, Emacs
1578 Run Emacs as a @dfn{daemon}, using the @samp{--daemon} command-line
1579 option. @xref{Initial Options}. When Emacs is started this way, it
1580 calls @code{server-start} after initialization, and returns control to
1581 the calling terminal instead of opening an initial frame; it then
1582 waits in the background, listening for edit requests.
1585 @cindex @env{TEXEDIT} environment variable
1586 Either way, once an Emacs server is started, you can use a shell
1587 command called @command{emacsclient} to connect to the Emacs process
1588 and tell it to visit a file. You can then set the @env{EDITOR}
1589 environment variable to @samp{emacsclient}, so that external programs
1590 will use the existing Emacs process for editing.@footnote{Some
1591 programs use a different environment variable; for example, to make
1592 @TeX{} use @samp{emacsclient}, set the @env{TEXEDIT} environment
1593 variable to @samp{emacsclient +%d %s}.}
1596 You can run multiple Emacs servers on the same machine by giving
1597 each one a unique @dfn{server name}, using the variable
1598 @code{server-name}. For example, @kbd{M-x set-variable @key{RET}
1599 server-name @key{RET} foo @key{RET}} sets the server name to
1600 @samp{foo}. The @code{emacsclient} program can specify a server by
1601 name, using the @samp{-s} option (@pxref{emacsclient Options}).
1603 @findex server-eval-at
1604 If you have defined a server by a unique server name, it is possible
1605 to connect to the server from another Emacs instance and evaluate Lisp
1606 expressions on the server, using the @code{server-eval-at} function.
1607 For instance, @code{(server-eval-at "foo" '(+ 1 2))} evaluates the
1608 expression @code{(+ 1 2)} on the @samp{foo} server, and returns
1609 @code{3}. (If there is no server with that name, an error is
1610 signaled.) Currently, this feature is mainly useful for developers.
1613 * Invoking emacsclient:: Connecting to the Emacs server.
1614 * emacsclient Options:: Emacs client startup options.
1617 @node Invoking emacsclient
1618 @subsection Invoking @code{emacsclient}
1619 @cindex @code{emacsclient} invocation
1621 The simplest way to use the @command{emacsclient} program is to run
1622 the shell command @samp{emacsclient @var{file}}, where @var{file} is a
1623 file name. This connects to an Emacs server, and tells that Emacs
1624 process to visit @var{file} in one of its existing frames---either a
1625 graphical frame, or one in a text terminal (@pxref{Frames}). You
1626 can then select that frame to begin editing.
1628 If there is no Emacs server, the @command{emacsclient} program halts
1629 with an error message. If the Emacs process has no existing
1630 frame---which can happen if it was started as a daemon (@pxref{Emacs
1631 Server})---then Emacs opens a frame on the terminal in which you
1632 called @command{emacsclient}.
1634 You can also force @command{emacsclient} to open a new frame on a
1635 graphical display, or on a text terminal, using the @samp{-c} and
1636 @samp{-t} options. @xref{emacsclient Options}.
1638 If you are running on a single text terminal, you can switch between
1639 @command{emacsclient}'s shell and the Emacs server using one of two
1640 methods: (i) run the Emacs server and @command{emacsclient} on
1641 different virtual terminals, and switch to the Emacs server's virtual
1642 terminal after calling @command{emacsclient}; or (ii) call
1643 @command{emacsclient} from within the Emacs server itself, using Shell
1644 mode (@pxref{Interactive Shell}) or Term mode (@pxref{Term Mode});
1645 @code{emacsclient} blocks only the subshell under Emacs, and you can
1646 still use Emacs to edit the file.
1650 When you finish editing @var{file} in the Emacs server, type
1651 @kbd{C-x #} (@code{server-edit}) in its buffer. This saves the file
1652 and sends a message back to the @command{emacsclient} program, telling
1653 it to exit. Programs that use @env{EDITOR} usually wait for the
1654 editor---in this case @command{emacsclient}---to exit before doing
1657 You can also call @command{emacsclient} with multiple file name
1658 arguments: @samp{emacsclient @var{file1} @var{file2} ...} tells the
1659 Emacs server to visit @var{file1}, @var{file2}, and so forth. Emacs
1660 selects the buffer visiting @var{file1}, and buries the other buffers
1661 at the bottom of the buffer list (@pxref{Buffers}). The
1662 @command{emacsclient} program exits once all the specified files are
1663 finished (i.e., once you have typed @kbd{C-x #} in each server
1666 @vindex server-kill-new-buffers
1667 @vindex server-temp-file-regexp
1668 Finishing with a server buffer also kills the buffer, unless it
1669 already existed in the Emacs session before the server was asked to
1670 create it. However, if you set @code{server-kill-new-buffers} to
1671 @code{nil}, then a different criterion is used: finishing with a
1672 server buffer kills it if the file name matches the regular expression
1673 @code{server-temp-file-regexp}. This is set up to distinguish certain
1676 Each @kbd{C-x #} checks for other pending external requests to edit
1677 various files, and selects the next such file. You can switch to a
1678 server buffer manually if you wish; you don't have to arrive at it
1679 with @kbd{C-x #}. But @kbd{C-x #} is the way to tell
1680 @command{emacsclient} that you are finished.
1682 @vindex server-window
1683 If you set the value of the variable @code{server-window} to a
1684 window or a frame, @kbd{C-x #} always displays the next server buffer
1685 in that window or in that frame.
1687 @node emacsclient Options
1688 @subsection @code{emacsclient} Options
1689 @cindex @code{emacsclient} options
1691 You can pass some optional arguments to the @command{emacsclient}
1695 emacsclient -c +12 @var{file1} +4:3 @var{file2}
1699 The @samp{+@var{line}} or @samp{+@var{line}:@var{column}} arguments
1700 specify line numbers, or line and column numbers, for the next file
1701 argument. These behave like the command line arguments for Emacs
1702 itself. @xref{Action Arguments}.
1704 The other optional arguments recognized by @command{emacsclient} are
1708 @item -a @var{command}
1709 @itemx --alternate-editor=@var{command}
1710 Specify a command to run if @code{emacsclient} fails to contact Emacs.
1711 This is useful when running @code{emacsclient} in a script.
1713 As a special exception, if @var{command} is the empty string, then
1714 @code{emacsclient} starts Emacs in daemon mode (as @command{emacs
1715 --daemon}) and then tries connecting again.
1717 @cindex @env{ALTERNATE_EDITOR} environment variable
1718 The environment variable @env{ALTERNATE_EDITOR} has the same effect as
1719 the @samp{-a} option. If both are present, the latter takes
1722 @cindex client frame
1724 @itemx --create-frame
1725 Create a new graphical @dfn{client frame}, instead of using an
1726 existing Emacs frame. See below for the special behavior of @kbd{C-x
1727 C-c} in a client frame. If Emacs cannot create a new graphical frame
1728 (e.g., if it cannot connect to the X server), it tries to create a
1729 text terminal client frame, as though you had supplied the @samp{-t}
1732 On MS-Windows, a single Emacs session cannot display frames on both
1733 graphical and text terminals, nor on multiple text terminals. Thus,
1734 if the Emacs server is running on a text terminal, the @samp{-c}
1735 option, like the @samp{-t} option, creates a new frame in the server's
1736 current text terminal. @xref{Windows Startup}.
1738 If you omit a filename argument while supplying the @samp{-c} option,
1739 the new frame displays the @file{*scratch*} buffer by default. You
1740 can customize this behavior with the variable @code{initial-buffer-choice}
1741 (@pxref{Entering Emacs}).
1743 @item -F @var{alist}
1744 @itemx --frame-parameters=@var{alist}
1745 Set the parameters for a newly-created graphical frame
1746 (@pxref{Frame Parameters}).
1748 @item -d @var{display}
1749 @itemx --display=@var{display}
1750 Tell Emacs to open the given files on the X display @var{display}
1751 (assuming there is more than one X display available).
1755 Tell Emacs to evaluate some Emacs Lisp code, instead of visiting some
1756 files. When this option is given, the arguments to
1757 @command{emacsclient} are interpreted as a list of expressions to
1758 evaluate, @emph{not} as a list of files to visit.
1760 @item -f @var{server-file}
1761 @itemx --server-file=@var{server-file}
1762 @cindex @env{EMACS_SERVER_FILE} environment variable
1763 Specify a @dfn{server file} for connecting to an Emacs server via TCP.
1765 An Emacs server usually uses a
1766 local socket to listen for connections. Some operating systems,
1767 such as Microsoft Windows, do not support local sockets; in that case,
1768 the server communicates with @command{emacsclient} via TCP.
1770 @vindex server-auth-dir
1773 When you start a TCP Emacs server, Emacs creates a @dfn{server file}
1774 containing the TCP information to be used by @command{emacsclient} to
1775 connect to the server. The variable @code{server-auth-dir} specifies
1776 the directory containing the server file; by default, this is
1777 @file{~/.emacs.d/server/}. To tell @command{emacsclient} to connect
1778 to the server over TCP with a specific server file, use the @samp{-f}
1779 or @samp{--server-file} option, or set the @env{EMACS_SERVER_FILE}
1780 environment variable.
1784 Let @command{emacsclient} exit immediately, instead of waiting until
1785 all server buffers are finished. You can take as long as you like to
1786 edit the server buffers within Emacs, and they are @emph{not} killed
1787 when you type @kbd{C-x #} in them.
1789 @item --parent-id @var{id}
1790 Open an @command{emacsclient} frame as a client frame in the parent X
1791 window with id @var{id}, via the XEmbed protocol. Currently, this
1792 option is mainly useful for developers.
1796 Do not let @command{emacsclient} display messages about waiting for
1797 Emacs or connecting to remote server sockets.
1799 @item -s @var{server-name}
1800 @itemx --socket-name=@var{server-name}
1801 Connect to the Emacs server named @var{server-name}. The server name
1802 is given by the variable @code{server-name} on the Emacs server. If
1803 this option is omitted, @command{emacsclient} connects to the first
1804 server it finds. (This option is not supported on MS-Windows.)
1809 Create a new client frame on the current text terminal, instead of
1810 using an existing Emacs frame. This behaves just like the @samp{-c}
1811 option, described above, except that it creates a text terminal frame
1812 (@pxref{Non-Window Terminals}).
1814 On MS-Windows, @samp{-t} behaves just like @samp{-c} if the Emacs
1815 server is using the graphical display, but if the Emacs server is
1816 running on a text terminal, it creates a new frame in the current text
1820 The new graphical or text terminal frames created by the @samp{-c}
1821 or @samp{-t} options are considered @dfn{client frames}. Any new
1822 frame that you create from a client frame is also considered a client
1823 frame. If you type @kbd{C-x C-c} (@code{save-buffers-kill-terminal})
1824 in a client frame, that command does not kill the Emacs session as it
1825 normally does (@pxref{Exiting}). Instead, Emacs deletes the client
1826 frame; furthermore, if the client frame has an @command{emacsclient}
1827 waiting to regain control (i.e., if you did not supply the @samp{-n}
1828 option), Emacs deletes all other frames of the same client, and marks
1829 the client's server buffers as finished, as though you had typed
1830 @kbd{C-x #} in all of them. If it so happens that there are no
1831 remaining frames after the client frame(s) are deleted, the Emacs
1834 As an exception, when Emacs is started as a daemon, all frames are
1835 considered client frames, and @kbd{C-x C-c} never kills Emacs. To
1836 kill a daemon session, type @kbd{M-x kill-emacs}.
1838 Note that the @samp{-t} and @samp{-n} options are contradictory:
1839 @samp{-t} says to take control of the current text terminal to create
1840 a new client frame, while @samp{-n} says not to take control of the
1841 text terminal. If you supply both options, Emacs visits the specified
1842 files(s) in an existing frame rather than a new client frame, negating
1843 the effect of @samp{-t}.
1846 @section Printing Hard Copies
1850 Emacs provides commands for printing hardcopies of either an entire
1851 buffer or part of one. You can invoke the printing commands directly,
1852 as detailed below, or using the @samp{File} menu on the menu bar.
1854 @findex htmlfontify-buffer
1855 Aside from the commands described in this section, you can also
1856 print hardcopies from Dired (@pxref{Operating on Files}) and the diary
1857 (@pxref{Displaying the Diary}). You can also ``print'' an Emacs
1858 buffer to HTML with the command @kbd{M-x htmlfontify-buffer}, which
1859 converts the current buffer to a HTML file, replacing Emacs faces with
1860 CSS-based markup. Furthermore, Org mode allows you to print Org
1861 files to a variety of formats, such as PDF (@pxref{Org Mode}).
1864 @item M-x print-buffer
1865 Print hardcopy of current buffer with page headings containing the
1866 file name and page number.
1867 @item M-x lpr-buffer
1868 Print hardcopy of current buffer without page headings.
1869 @item M-x print-region
1870 Like @code{print-buffer} but print only the current region.
1871 @item M-x lpr-region
1872 Like @code{lpr-buffer} but print only the current region.
1875 @findex print-buffer
1876 @findex print-region
1879 @vindex lpr-switches
1880 @vindex lpr-commands
1881 On most operating system, the above hardcopy commands submit files
1882 for printing by calling the @command{lpr} program. To change the
1883 printer program, customize the variable @code{lpr-command}. To
1884 specify extra switches to give the printer program, customize the list
1885 variable @code{lpr-switches}. Its value should be a list of option
1886 strings, each of which should start with @samp{-} (e.g., the option
1887 string @code{"-w80"} specifies a line width of 80 columns). The
1888 default is the empty list, @code{nil}.
1890 @vindex printer-name
1891 @vindex lpr-printer-switch
1892 To specify the printer to use, set the variable @code{printer-name}.
1893 The default, @code{nil}, specifies the default printer. If you set it
1894 to a printer name (a string), that name is passed to @command{lpr}
1895 with the @samp{-P} switch; if you are not using @command{lpr}, you
1896 should specify the switch with @code{lpr-printer-switch}.
1898 @vindex lpr-headers-switches
1899 @vindex lpr-add-switches
1900 The variable @code{lpr-headers-switches} similarly specifies the
1901 extra switches to use to make page headers. The variable
1902 @code{lpr-add-switches} controls whether to supply @samp{-T} and
1903 @samp{-J} options (suitable for @command{lpr}) to the printer program:
1904 @code{nil} means don't add them (this should be the value if your
1905 printer program is not compatible with @command{lpr}).
1908 * PostScript:: Printing buffers or regions as PostScript.
1909 * PostScript Variables:: Customizing the PostScript printing commands.
1910 * Printing Package:: An optional advanced printing interface.
1914 @subsection PostScript Hardcopy
1916 These commands convert buffer contents to PostScript,
1917 either printing it or leaving it in another Emacs buffer.
1920 @item M-x ps-print-buffer
1921 Print hardcopy of the current buffer in PostScript form.
1922 @item M-x ps-print-region
1923 Print hardcopy of the current region in PostScript form.
1924 @item M-x ps-print-buffer-with-faces
1925 Print hardcopy of the current buffer in PostScript form, showing the
1926 faces used in the text by means of PostScript features.
1927 @item M-x ps-print-region-with-faces
1928 Print hardcopy of the current region in PostScript form, showing the
1929 faces used in the text.
1930 @item M-x ps-spool-buffer
1931 Generate and spool a PostScript image for the current buffer text.
1932 @item M-x ps-spool-region
1933 Generate and spool a PostScript image for the current region.
1934 @item M-x ps-spool-buffer-with-faces
1935 Generate and spool a PostScript image for the current buffer, showing the faces used.
1936 @item M-x ps-spool-region-with-faces
1937 Generate and spool a PostScript image for the current region, showing the faces used.
1938 @item M-x ps-despool
1939 Send the spooled PostScript to the printer.
1941 Generate/print PostScript for the current buffer as if handwritten.
1944 @findex ps-print-region
1945 @findex ps-print-buffer
1946 @findex ps-print-region-with-faces
1947 @findex ps-print-buffer-with-faces
1948 The @code{ps-print-buffer} and @code{ps-print-region} commands print
1949 buffer contents in PostScript form. One command prints the entire
1950 buffer; the other, just the region. The commands
1951 @code{ps-print-buffer-with-faces} and
1952 @code{ps-print-region-with-faces} behave similarly, but use PostScript
1953 features to show the faces (fonts and colors) of the buffer text.
1955 Interactively, when you use a prefix argument (@kbd{C-u}), the command
1956 prompts the user for a file name, and saves the PostScript image in that file
1957 instead of sending it to the printer.
1959 @findex ps-spool-region
1960 @findex ps-spool-buffer
1961 @findex ps-spool-region-with-faces
1962 @findex ps-spool-buffer-with-faces
1963 The commands whose names have @samp{spool} instead of @samp{print},
1964 generate the PostScript output in an Emacs buffer instead of sending
1968 Use the command @code{ps-despool} to send the spooled images to the
1969 printer. This command sends the PostScript generated by
1970 @samp{-spool-} commands (see commands above) to the printer. With a
1971 prefix argument (@kbd{C-u}), it prompts for a file name, and saves the
1972 spooled PostScript image in that file instead of sending it to the
1977 @kbd{M-x handwrite} is more frivolous. It generates a PostScript
1978 rendition of the current buffer as a cursive handwritten document. It
1979 can be customized in group @code{handwrite}. This function only
1980 supports ISO 8859-1 characters.
1982 @node PostScript Variables
1983 @subsection Variables for PostScript Hardcopy
1985 @vindex ps-lpr-command
1986 @vindex ps-lpr-switches
1987 @vindex ps-printer-name
1988 All the PostScript hardcopy commands use the variables
1989 @code{ps-lpr-command} and @code{ps-lpr-switches} to specify how to print
1990 the output. @code{ps-lpr-command} specifies the command name to run,
1991 @code{ps-lpr-switches} specifies command line options to use, and
1992 @code{ps-printer-name} specifies the printer. If you don't set the
1993 first two variables yourself, they take their initial values from
1994 @code{lpr-command} and @code{lpr-switches}. If @code{ps-printer-name}
1995 is @code{nil}, @code{printer-name} is used.
1997 @vindex ps-print-header
1998 The variable @code{ps-print-header} controls whether these commands
1999 add header lines to each page---set it to @code{nil} to turn headers
2002 @cindex color emulation on black-and-white printers
2003 @vindex ps-print-color-p
2004 If your printer doesn't support colors, you should turn off color
2005 processing by setting @code{ps-print-color-p} to @code{nil}. By
2006 default, if the display supports colors, Emacs produces hardcopy output
2007 with color information; on black-and-white printers, colors are emulated
2008 with shades of gray. This might produce illegible output, even if your
2009 screen colors only use shades of gray.
2011 Alternatively, you can set @code{ps-print-color-p} to @code{black-white} to
2012 print colors on black/white printers.
2014 @vindex ps-use-face-background
2015 By default, PostScript printing ignores the background colors of the
2016 faces, unless the variable @code{ps-use-face-background} is
2017 non-@code{nil}. This is to avoid unwanted interference with the zebra
2018 stripes and background image/text.
2020 @vindex ps-paper-type
2021 @vindex ps-page-dimensions-database
2022 The variable @code{ps-paper-type} specifies which size of paper to
2023 format for; legitimate values include @code{a4}, @code{a3},
2024 @code{a4small}, @code{b4}, @code{b5}, @code{executive}, @code{ledger},
2025 @code{legal}, @code{letter}, @code{letter-small}, @code{statement},
2026 @code{tabloid}. The default is @code{letter}. You can define
2027 additional paper sizes by changing the variable
2028 @code{ps-page-dimensions-database}.
2030 @vindex ps-landscape-mode
2031 The variable @code{ps-landscape-mode} specifies the orientation of
2032 printing on the page. The default is @code{nil}, which stands for
2033 portrait mode. Any non-@code{nil} value specifies landscape
2036 @vindex ps-number-of-columns
2037 The variable @code{ps-number-of-columns} specifies the number of
2038 columns; it takes effect in both landscape and portrait mode. The
2041 @vindex ps-font-family
2042 @vindex ps-font-size
2043 @vindex ps-font-info-database
2044 The variable @code{ps-font-family} specifies which font family to use
2045 for printing ordinary text. Legitimate values include @code{Courier},
2046 @code{Helvetica}, @code{NewCenturySchlbk}, @code{Palatino} and
2047 @code{Times}. The variable @code{ps-font-size} specifies the size of
2048 the font for ordinary text. It defaults to 8.5 points.
2050 @vindex ps-multibyte-buffer
2051 @cindex Intlfonts for PostScript printing
2052 @cindex fonts for PostScript printing
2053 Emacs supports more scripts and characters than a typical PostScript
2054 printer. Thus, some of the characters in your buffer might not be
2055 printable using the fonts built into your printer. You can augment
2056 the fonts supplied with the printer with those from the GNU Intlfonts
2057 package, or you can instruct Emacs to use Intlfonts exclusively. The
2058 variable @code{ps-multibyte-buffer} controls this: the default value,
2059 @code{nil}, is appropriate for printing @acronym{ASCII} and Latin-1
2060 characters; a value of @code{non-latin-printer} is for printers which
2061 have the fonts for @acronym{ASCII}, Latin-1, Japanese, and Korean
2062 characters built into them. A value of @code{bdf-font} arranges for
2063 the BDF fonts from the Intlfonts package to be used for @emph{all}
2064 characters. Finally, a value of @code{bdf-font-except-latin}
2065 instructs the printer to use built-in fonts for @acronym{ASCII} and Latin-1
2066 characters, and Intlfonts BDF fonts for the rest.
2068 @vindex bdf-directory-list
2069 To be able to use the BDF fonts, Emacs needs to know where to find
2070 them. The variable @code{bdf-directory-list} holds the list of
2071 directories where Emacs should look for the fonts; the default value
2072 includes a single directory @file{/usr/local/share/emacs/fonts/bdf}.
2074 Many other customization variables for these commands are defined and
2075 described in the Lisp files @file{ps-print.el} and @file{ps-mule.el}.
2077 @node Printing Package
2078 @subsection Printing Package
2079 @cindex Printing package
2081 The basic Emacs facilities for printing hardcopy can be extended
2082 using the Printing package. This provides an easy-to-use interface
2083 for choosing what to print, previewing PostScript files before
2084 printing, and setting various printing options such as print headers,
2085 landscape or portrait modes, duplex modes, and so forth. On GNU/Linux
2086 or Unix systems, the Printing package relies on the @file{gs} and
2087 @file{gv} utilities, which are distributed as part of the GhostScript
2088 program. On MS-Windows, the @file{gstools} port of Ghostscript can be
2091 @findex pr-interface
2092 To use the Printing package, add @code{(require 'printing)} to your
2093 init file (@pxref{Init File}), followed by @code{(pr-update-menus)}.
2094 This function replaces the usual printing commands in the menu bar
2095 with a @samp{Printing} submenu that contains various printing options.
2096 You can also type @kbd{M-x pr-interface @key{RET}}; this creates a
2097 @file{*Printing Interface*} buffer, similar to a customization buffer,
2098 where you can set the printing options. After selecting what and how
2099 to print, you start the print job using the @samp{Print} button (click
2100 @kbd{Mouse-2} on it, or move point over it and type @key{RET}). For
2101 further information on the various options, use the @samp{Interface
2105 @section Sorting Text
2108 Emacs provides several commands for sorting text in the buffer. All
2109 operate on the contents of the region.
2110 They divide the text of the region into many @dfn{sort records},
2111 identify a @dfn{sort key} for each record, and then reorder the records
2112 into the order determined by the sort keys. The records are ordered so
2113 that their keys are in alphabetical order, or, for numeric sorting, in
2114 numeric order. In alphabetic sorting, all upper-case letters @samp{A}
2115 through @samp{Z} come before lower-case @samp{a}, in accordance with the
2116 @acronym{ASCII} character sequence.
2118 The various sort commands differ in how they divide the text into sort
2119 records and in which part of each record is used as the sort key. Most of
2120 the commands make each line a separate sort record, but some commands use
2121 paragraphs or pages as sort records. Most of the sort commands use each
2122 entire sort record as its own sort key, but some use only a portion of the
2123 record as the sort key.
2126 @findex sort-paragraphs
2129 @findex sort-numeric-fields
2130 @vindex sort-numeric-base
2132 @item M-x sort-lines
2133 Divide the region into lines, and sort by comparing the entire
2134 text of a line. A numeric argument means sort into descending order.
2136 @item M-x sort-paragraphs
2137 Divide the region into paragraphs, and sort by comparing the entire
2138 text of a paragraph (except for leading blank lines). A numeric
2139 argument means sort into descending order.
2141 @item M-x sort-pages
2142 Divide the region into pages, and sort by comparing the entire
2143 text of a page (except for leading blank lines). A numeric
2144 argument means sort into descending order.
2146 @item M-x sort-fields
2147 Divide the region into lines, and sort by comparing the contents of
2148 one field in each line. Fields are defined as separated by
2149 whitespace, so the first run of consecutive non-whitespace characters
2150 in a line constitutes field 1, the second such run constitutes field
2153 Specify which field to sort by with a numeric argument: 1 to sort by
2154 field 1, etc. A negative argument means count fields from the right
2155 instead of from the left; thus, minus 1 means sort by the last field.
2156 If several lines have identical contents in the field being sorted, they
2157 keep the same relative order that they had in the original buffer.
2159 @item M-x sort-numeric-fields
2160 Like @kbd{M-x sort-fields} except the specified field is converted
2161 to an integer for each line, and the numbers are compared. @samp{10}
2162 comes before @samp{2} when considered as text, but after it when
2163 considered as a number. By default, numbers are interpreted according
2164 to @code{sort-numeric-base}, but numbers beginning with @samp{0x} or
2165 @samp{0} are interpreted as hexadecimal and octal, respectively.
2167 @item M-x sort-columns
2168 Like @kbd{M-x sort-fields} except that the text within each line
2169 used for comparison comes from a fixed range of columns. With a
2170 prefix argument, sort in reverse order. See below for more details
2173 @findex reverse-region
2174 @item M-x reverse-region
2175 Reverse the order of the lines in the region. This is useful for
2176 sorting into descending order by fields, since those sort
2177 commands do not have a feature for doing that.
2180 For example, if the buffer contains this:
2183 On systems where clash detection (locking of files being edited) is
2184 implemented, Emacs also checks the first time you modify a buffer
2185 whether the file has changed on disk since it was last visited or
2186 saved. If it has, you are asked to confirm that you want to change
2191 applying @kbd{M-x sort-lines} to the entire buffer produces this:
2194 On systems where clash detection (locking of files being edited) is
2195 implemented, Emacs also checks the first time you modify a buffer
2196 saved. If it has, you are asked to confirm that you want to change
2198 whether the file has changed on disk since it was last visited or
2202 where the upper-case @samp{O} sorts before all lower-case letters. If
2203 you use @kbd{C-u 2 M-x sort-fields} instead, you get this:
2206 implemented, Emacs also checks the first time you modify a buffer
2207 saved. If it has, you are asked to confirm that you want to change
2209 On systems where clash detection (locking of files being edited) is
2210 whether the file has changed on disk since it was last visited or
2214 where the sort keys were @samp{Emacs}, @samp{If}, @samp{buffer},
2215 @samp{systems} and @samp{the}.
2217 @findex sort-columns
2218 @kbd{M-x sort-columns} requires more explanation. You specify the
2219 columns by putting point at one of the columns and the mark at the other
2220 column. Because this means you cannot put point or the mark at the
2221 beginning of the first line of the text you want to sort, this command
2222 uses an unusual definition of ``region'': all of the line point is in is
2223 considered part of the region, and so is all of the line the mark is in,
2224 as well as all the lines in between.
2226 For example, to sort a table by information found in columns 10 to 15,
2227 you could put the mark on column 10 in the first line of the table, and
2228 point on column 15 in the last line of the table, and then run
2229 @code{sort-columns}. Equivalently, you could run it with the mark on
2230 column 15 in the first line and point on column 10 in the last line.
2232 This can be thought of as sorting the rectangle specified by point and
2233 the mark, except that the text on each line to the left or right of the
2234 rectangle moves along with the text inside the rectangle.
2237 @vindex sort-fold-case
2238 Many of the sort commands ignore case differences when comparing, if
2239 @code{sort-fold-case} is non-@code{nil}.
2241 @c Picture Mode documentation
2243 @include picture-xtra.texi
2247 @node Editing Binary Files
2248 @section Editing Binary Files
2252 @cindex editing binary files
2254 There is a special major mode for editing binary files: Hexl mode. To
2255 use it, use @kbd{M-x hexl-find-file} instead of @kbd{C-x C-f} to visit
2256 the file. This command converts the file's contents to hexadecimal and
2257 lets you edit the translation. When you save the file, it is converted
2258 automatically back to binary.
2260 You can also use @kbd{M-x hexl-mode} to translate an existing buffer
2261 into hex. This is useful if you visit a file normally and then discover
2262 it is a binary file.
2264 Ordinary text characters overwrite in Hexl mode. This is to reduce
2265 the risk of accidentally spoiling the alignment of data in the file.
2266 There are special commands for insertion. Here is a list of the
2267 commands of Hexl mode:
2269 @c I don't think individual index entries for these commands are useful--RMS.
2272 Insert a byte with a code typed in decimal.
2275 Insert a byte with a code typed in octal.
2278 Insert a byte with a code typed in hex.
2281 Move to the beginning of a 1k-byte page.
2284 Move to the end of a 1k-byte page.
2287 Move to an address specified in hex.
2290 Move to an address specified in decimal.
2293 Leave Hexl mode, going back to the major mode this buffer had before you
2294 invoked @code{hexl-mode}.
2298 Other Hexl commands let you insert strings (sequences) of binary
2299 bytes, move by @code{short}s or @code{int}s, etc.; type @kbd{C-h a
2300 hexl-@key{RET}} for details.
2303 @node Saving Emacs Sessions
2304 @section Saving Emacs Sessions
2305 @cindex saving sessions
2306 @cindex restore session
2307 @cindex remember editing session
2308 @cindex reload files
2311 @vindex desktop-restore-frames
2312 Use the desktop library to save the state of Emacs from one session
2313 to another. Once you save the Emacs @dfn{desktop}---the buffers,
2314 their file names, major modes, buffer positions, and so on---then
2315 subsequent Emacs sessions reload the saved desktop. By default,
2316 the desktop also tries to save the frame and window configuration.
2317 To disable this, set @code{desktop-restore-frames} to @code{nil}.
2318 (See that variable's documentation for some related options
2319 that you can customize to fine-tune this behavior.)
2321 @findex desktop-save
2322 @vindex desktop-save-mode
2323 You can save the desktop manually with the command @kbd{M-x
2324 desktop-save}. You can also enable automatic saving of the desktop
2325 when you exit Emacs, and automatic restoration of the last saved
2326 desktop when Emacs starts: use the Customization buffer (@pxref{Easy
2327 Customization}) to set @code{desktop-save-mode} to @code{t} for future
2328 sessions, or add this line in your init file (@pxref{Init File}):
2331 (desktop-save-mode 1)
2334 @vindex desktop-auto-save-timeout
2336 When @code{desktop-save-mode} is active and the desktop file exists,
2337 Emacs auto-saves it every @code{desktop-auto-save-timeout}
2338 seconds, if that is non-@code{nil} and non-zero.
2340 @findex desktop-change-dir
2341 @findex desktop-revert
2342 @vindex desktop-path
2343 If you turn on @code{desktop-save-mode} in your init file, then when
2344 Emacs starts, it looks for a saved desktop in the current directory.
2345 (More precisely, it looks in the directories specified by
2346 @var{desktop-path}, and uses the first desktop it finds.)
2347 Thus, you can have separate saved desktops in different directories,
2348 and the starting directory determines which one Emacs reloads. You
2349 can save the current desktop and reload one saved in another directory
2350 by typing @kbd{M-x desktop-change-dir}. Typing @kbd{M-x
2351 desktop-revert} reverts to the desktop previously reloaded.
2353 Specify the option @samp{--no-desktop} on the command line when you
2354 don't want it to reload any saved desktop. This turns off
2355 @code{desktop-save-mode} for the current session. Starting Emacs with
2356 the @samp{--no-init-file} option also disables desktop reloading,
2357 since it bypasses the init file, where @code{desktop-save-mode} is
2360 @vindex desktop-restore-eager
2361 By default, all the buffers in the desktop are restored at one go.
2362 However, this may be slow if there are a lot of buffers in the
2363 desktop. You can specify the maximum number of buffers to restore
2364 immediately with the variable @code{desktop-restore-eager}; the
2365 remaining buffers are restored lazily, when Emacs is idle.
2367 @findex desktop-clear
2368 @vindex desktop-globals-to-clear
2369 @vindex desktop-clear-preserve-buffers-regexp
2370 Type @kbd{M-x desktop-clear} to empty the Emacs desktop. This kills
2371 all buffers except for internal ones, and clears the global variables
2372 listed in @code{desktop-globals-to-clear}. If you want this to
2373 preserve certain buffers, customize the variable
2374 @code{desktop-clear-preserve-buffers-regexp}, whose value is a regular
2375 expression matching the names of buffers not to kill.
2377 If you want to save minibuffer history from one session to
2378 another, use the @code{savehist} library.
2380 @node Recursive Edit
2381 @section Recursive Editing Levels
2382 @cindex recursive editing level
2383 @cindex editing level, recursive
2385 A @dfn{recursive edit} is a situation in which you are using Emacs
2386 commands to perform arbitrary editing while in the middle of another
2387 Emacs command. For example, when you type @kbd{C-r} inside of a
2388 @code{query-replace}, you enter a recursive edit in which you can change
2389 the current buffer. On exiting from the recursive edit, you go back to
2390 the @code{query-replace}. @xref{Query Replace}.
2393 @findex exit-recursive-edit
2394 @cindex exiting recursive edit
2395 @dfn{Exiting} the recursive edit means returning to the unfinished
2396 command, which continues execution. The command to exit is @kbd{C-M-c}
2397 (@code{exit-recursive-edit}).
2399 You can also @dfn{abort} the recursive edit. This is like exiting,
2400 but also quits the unfinished command immediately. Use the command
2401 @kbd{C-]} (@code{abort-recursive-edit}) to do this. @xref{Quitting}.
2403 The mode line shows you when you are in a recursive edit by displaying
2404 square brackets around the parentheses that always surround the major and
2405 minor mode names. Every window's mode line shows this in the same way,
2406 since being in a recursive edit is true of Emacs as a whole rather than
2407 any particular window or buffer.
2409 It is possible to be in recursive edits within recursive edits. For
2410 example, after typing @kbd{C-r} in a @code{query-replace}, you may type a
2411 command that enters the debugger. This begins a recursive editing level
2412 for the debugger, within the recursive editing level for @kbd{C-r}.
2413 Mode lines display a pair of square brackets for each recursive editing
2414 level currently in progress.
2416 Exiting the inner recursive edit (such as with the debugger @kbd{c}
2417 command) resumes the command running in the next level up. When that
2418 command finishes, you can then use @kbd{C-M-c} to exit another recursive
2419 editing level, and so on. Exiting applies to the innermost level only.
2420 Aborting also gets out of only one level of recursive edit; it returns
2421 immediately to the command level of the previous recursive edit. If you
2422 wish, you can then abort the next recursive editing level.
2424 Alternatively, the command @kbd{M-x top-level} aborts all levels of
2425 recursive edits, returning immediately to the top-level command
2426 reader. It also exits the minibuffer, if it is active.
2428 The text being edited inside the recursive edit need not be the same text
2429 that you were editing at top level. It depends on what the recursive edit
2430 is for. If the command that invokes the recursive edit selects a different
2431 buffer first, that is the buffer you will edit recursively. In any case,
2432 you can switch buffers within the recursive edit in the normal manner (as
2433 long as the buffer-switching keys have not been rebound). You could
2434 probably do all the rest of your editing inside the recursive edit,
2435 visiting files and all. But this could have surprising effects (such as
2436 stack overflow) from time to time. So remember to exit or abort the
2437 recursive edit when you no longer need it.
2439 In general, we try to minimize the use of recursive editing levels in
2440 GNU Emacs. This is because they constrain you to go back in a
2441 particular order---from the innermost level toward the top level. When
2442 possible, we present different activities in separate buffers so that
2443 you can switch between them as you please. Some commands switch to a
2444 new major mode which provides a command to switch back. These
2445 approaches give you more flexibility to go back to unfinished tasks in
2446 the order you choose.
2449 @c Apart from edt and viper, this is all obsolete.
2450 @c (Can't believe we were saying "most other editors" into 2014!)
2451 @c There seems no point having a node just for those, which both have
2452 @c their own manuals.
2455 @cindex emulating other editors
2456 @cindex other editors
2461 GNU Emacs can be programmed to emulate (more or less) most other
2462 editors. Standard facilities can emulate these:
2465 @item CRiSP/Brief (PC editor)
2467 @vindex crisp-override-meta-x
2468 @findex scroll-all-mode
2470 @cindex Brief emulation
2471 @cindex emulation of Brief
2473 @kbd{M-x crisp-mode} enables key bindings to emulate the CRiSP/Brief
2474 editor. Note that this rebinds @kbd{M-x} to exit Emacs unless you set
2475 the variable @code{crisp-override-meta-x}. You can also use the
2476 command @kbd{M-x scroll-all-mode} or set the variable
2477 @code{crisp-load-scroll-all} to emulate CRiSP's scroll-all feature
2478 (scrolling all windows together).
2480 @item EDT (DEC VMS editor)
2481 @findex edt-emulation-on
2482 @findex edt-emulation-off
2483 Turn on EDT emulation with @kbd{M-x edt-emulation-on}; restore normal
2484 command bindings with @kbd{M-x edt-emulation-off}.
2486 Most of the EDT emulation commands are keypad keys, and most standard
2487 Emacs key bindings are still available. The EDT emulation rebindings
2488 are done in the global keymap, so there is no problem switching
2489 buffers or major modes while in EDT emulation.
2491 @item TPU (DEC VMS editor)
2494 @kbd{M-x tpu-edt-on} turns on emulation of the TPU editor emulating EDT.
2496 @item vi (Berkeley editor)
2498 Viper is an emulator for vi. It implements several levels of
2499 emulation; level 1 is closest to vi itself, while level 5 departs
2500 somewhat from strict emulation to take advantage of the capabilities of
2501 Emacs. To invoke Viper, type @kbd{M-x viper-mode}; it will guide you
2502 the rest of the way and ask for the emulation level. @inforef{Top,
2505 @item vi (another emulator)
2507 @kbd{M-x vi-mode} enters a major mode that replaces the previously
2508 established major mode. All of the vi commands that, in real vi, enter
2509 input mode are programmed instead to return to the previous major
2510 mode. Thus, ordinary Emacs serves as vi's input mode.
2512 Because vi emulation works through major modes, it does not work
2513 to switch buffers during emulation. Return to normal Emacs first.
2515 If you plan to use vi emulation much, you probably want to bind a key
2516 to the @code{vi-mode} command.
2518 @item vi (alternate emulator)
2520 @kbd{M-x vip-mode} invokes another vi emulator, said to resemble real vi
2521 more thoroughly than @kbd{M-x vi-mode}. Input mode in this emulator
2522 is changed from ordinary Emacs so you can use @key{ESC} to go back to
2523 emulated vi command mode. To get from emulated vi command mode back to
2524 ordinary Emacs, type @kbd{C-z}.
2526 This emulation does not work through major modes, and it is possible
2527 to switch buffers in various ways within the emulator. It is not
2528 so necessary to assign a key to the command @code{vip-mode} as
2529 it is with @code{vi-mode} because terminating insert mode does
2532 @inforef{Top, VIP, vip}, for full information.
2534 @item WordStar (old wordprocessor)
2535 @findex wordstar-mode
2536 @kbd{M-x wordstar-mode} provides a major mode with WordStar-like
2543 @section Hyperlinking and Navigation Features
2545 The following subsections describe convenience features for handling
2546 URLs and other types of links occurring in Emacs buffer text.
2549 * Browse-URL:: Following URLs.
2550 * Goto Address mode:: Activating URLs.
2551 * FFAP:: Finding files etc. at point.
2555 @subsection Following URLs
2556 @cindex World Wide Web
2559 @findex browse-url-at-point
2560 @findex browse-url-at-mouse
2565 @item M-x browse-url @key{RET} @var{url} @key{RET}
2566 Load a URL into a Web browser.
2569 The Browse-URL package allows you to easily follow URLs from within
2570 Emacs. Most URLs are followed by invoking a web browser;
2571 @samp{mailto:} URLs are followed by invoking the @code{compose-mail}
2572 Emacs command to send mail to the specified address (@pxref{Sending
2575 The command @kbd{M-x browse-url} prompts for a URL, and follows it.
2576 If point is located near a plausible URL, that URL is offered as the
2577 default. The Browse-URL package also provides other commands which
2578 you might like to bind to keys, such as @code{browse-url-at-point} and
2579 @code{browse-url-at-mouse}.
2581 @vindex browse-url-mailto-function
2582 @vindex browse-url-browser-function
2583 You can customize Browse-URL's behavior via various options in the
2584 @code{browse-url} Customize group. In particular, the option
2585 @code{browse-url-mailto-function} lets you define how to follow
2586 @samp{mailto:} URLs, while @code{browse-url-browser-function} lets you
2587 define how to follow other types of URLs. For more information, view
2588 the package commentary by typing @kbd{C-h P browse-url @key{RET}}.
2590 @node Goto Address mode
2591 @subsection Activating URLs
2592 @findex goto-address-mode
2593 @cindex mode, Goto Address
2594 @cindex Goto Address mode
2595 @cindex URLs, activating
2598 @item M-x goto-address-mode
2599 Activate URLs and e-mail addresses in the current buffer.
2602 @kindex C-c RET @r{(Goto Address mode)}
2603 @findex goto-address-at-point
2604 You can make Emacs mark out URLs specially in the current buffer, by
2605 typing @kbd{M-x goto-address-mode}. When this buffer-local minor mode
2606 is enabled, it finds all the URLs in the buffer, highlights them, and
2607 turns them into clickable buttons. You can follow the URL by typing
2608 @kbd{C-c @key{RET}} (@code{goto-address-at-point}) while point is on
2609 its text; or by clicking with @kbd{Mouse-2}, or by clicking
2610 @kbd{Mouse-1} quickly (@pxref{Mouse References}). Following a URL is
2611 done by calling @code{browse-url} as a subroutine
2612 (@pxref{Browse-URL}).
2614 It can be useful to add @code{goto-address-mode} to mode hooks and
2615 hooks for displaying an incoming message
2616 (e.g., @code{rmail-show-message-hook} for Rmail, and
2617 @code{mh-show-mode-hook} for MH-E). This is not needed for Gnus,
2618 which has a similar feature of its own.
2621 @subsection Finding Files and URLs at Point
2622 @findex find-file-at-point
2624 @findex dired-at-point
2627 @cindex finding file at point
2629 The FFAP package replaces certain key bindings for finding files,
2630 such as @kbd{C-x C-f}, with commands that provide more sensitive
2631 defaults. These commands behave like the ordinary ones when given a
2632 prefix argument. Otherwise, they get the default file name or URL
2633 from the text around point. If what is found in the buffer has the
2634 form of a URL rather than a file name, the commands use
2635 @code{browse-url} to view it (@pxref{Browse-URL}).
2637 This feature is useful for following references in mail or news
2638 buffers, @file{README} files, @file{MANIFEST} files, and so on. For
2639 more information, view the package commentary by typing @kbd{C-h P
2642 @cindex FFAP minor mode
2644 To enable FFAP, type @kbd{M-x ffap-bindings}. This makes the
2645 following key bindings, and also installs hooks for additional FFAP
2646 functionality in Rmail, Gnus and VM article buffers.
2649 @item C-x C-f @var{filename} @key{RET}
2650 @kindex C-x C-f @r{(FFAP)}
2651 Find @var{filename}, guessing a default from text around point
2652 (@code{find-file-at-point}).
2654 @kindex C-x C-r @r{(FFAP)}
2655 @code{ffap-read-only}, analogous to @code{find-file-read-only}.
2657 @kindex C-x C-v @r{(FFAP)}
2658 @code{ffap-alternate-file}, analogous to @code{find-alternate-file}.
2659 @item C-x d @var{directory} @key{RET}
2660 @kindex C-x d @r{(FFAP)}
2661 Start Dired on @var{directory}, defaulting to the directory name at
2662 point (@code{dired-at-point}).
2664 @code{ffap-list-directory}, analogous to @code{list-directory}.
2666 @kindex C-x 4 f @r{(FFAP)}
2667 @code{ffap-other-window}, analogous to @code{find-file-other-window}.
2669 @code{ffap-read-only-other-window}, analogous to
2670 @code{find-file-read-only-other-window}.
2672 @code{ffap-dired-other-window}, like @code{dired-other-window}.
2674 @kindex C-x 5 f @r{(FFAP)}
2675 @code{ffap-other-frame}, analogous to @code{find-file-other-frame}.
2677 @code{ffap-read-only-other-frame}, analogous to
2678 @code{find-file-read-only-other-frame}.
2680 @code{ffap-dired-other-frame}, analogous to @code{dired-other-frame}.
2682 Search buffer for next file name or URL, then find that file or URL.
2684 @kindex S-Mouse-3 @r{(FFAP)}
2685 @code{ffap-at-mouse} finds the file guessed from text around the position
2688 @kindex C-S-Mouse-3 @r{(FFAP)}
2689 Display a menu of files and URLs mentioned in current buffer, then
2690 find the one you select (@code{ffap-menu}).
2694 @section Other Amusements
2697 @findex animate-birthday-present
2699 The @code{animate} package makes text dance (e.g., @kbd{M-x
2700 animate-birthday-present}).
2706 @kbd{M-x blackbox}, @kbd{M-x mpuz} and @kbd{M-x 5x5} are puzzles.
2707 @code{blackbox} challenges you to determine the location of objects
2708 inside a box by tomography. @code{mpuz} displays a multiplication
2709 puzzle with letters standing for digits in a code that you must
2710 guess---to guess a value, type a letter and then the digit you think it
2711 stands for. The aim of @code{5x5} is to fill in all the squares.
2714 @kbd{M-x bubbles} is a game in which the object is to remove as many
2715 bubbles as you can in the smallest number of moves.
2719 @cindex cryptanalysis
2720 @kbd{M-x decipher} helps you to cryptanalyze a buffer which is
2721 encrypted in a simple monoalphabetic substitution cipher.
2723 @findex dissociated-press
2724 @kbd{M-x dissociated-press} scrambles the text in the current Emacs
2725 buffer, word by word or character by character, writing its output to
2726 a buffer named @file{*Dissociation*}. A positive argument tells it to
2727 operate character by character, and specifies the number of overlap
2728 characters. A negative argument tells it to operate word by word, and
2729 specifies the number of overlap words. Dissociated Press produces
2730 results fairly like those of a Markov chain, but is however, an
2731 independent, ignoriginal invention; it techniquitously copies several
2732 consecutive characters from the sample text between random jumps,
2733 unlike a Markov chain which would jump randomly after each word or
2734 character. Keep dissociwords out of your documentation, if you want
2735 it to be well userenced and properbose.
2738 @kbd{M-x dunnet} runs a text-based adventure game.
2742 If you want a little more personal involvement, try @kbd{M-x gomoku},
2743 which plays the game Go Moku with you.
2745 @cindex tower of Hanoi
2747 If you are a little bit bored, you can try @kbd{M-x hanoi}. If you are
2748 considerably bored, give it a numeric argument. If you are very, very
2749 bored, try an argument of 9. Sit back and watch.
2753 @kbd{M-x life} runs Conway's Game of Life cellular automaton.
2756 @cindex landmark game
2757 @kbd{M-x landmark} runs a relatively non-participatory game in which
2758 a robot attempts to maneuver towards a tree at the center of the
2759 window based on unique olfactory cues from each of the four
2762 @findex morse-region
2763 @findex unmorse-region
2766 @cindex --/---/.-./.../.
2767 @kbd{M-x morse-region} converts the text in the region to Morse
2768 code; @kbd{M-x unmorse-region} converts it back. @kbd{M-x
2769 nato-region} converts the text in the region to NATO phonetic
2770 alphabet; @kbd{M-x denato-region} converts it back.
2778 @kbd{M-x pong}, @kbd{M-x snake} and @kbd{M-x tetris} are
2779 implementations of the well-known Pong, Snake and Tetris games.
2783 @kbd{M-x solitaire} plays a game of solitaire in which you jump pegs
2787 The command @kbd{M-x zone} plays games with the display when Emacs
2792 Finally, if you find yourself frustrated, try describing your
2793 problems to the famous psychotherapist Eliza. Just do @kbd{M-x
2794 doctor}. End each input by typing @key{RET} twice.